Summer '21

GREENSCAPE 

Ensuring Best Practice for Green Roof & Solar PV Projects MAGAZINE 

SUMMER 2021 

GRO Code in Detail 

Blue-Green Roofs 

Green Talk: Q&A 

Academic Corner: Biosolar 

News, Views and Projects 

Green Roof Mythbusters 

In collaboration with the Green Roof Organisation

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3 | Working Towards Zero Avoidable Waste in the Roofing Sector 

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GREENSCAPE 

IN THIS ISSUE... 

Matt Downs 

Editorial Director 

mattdowns@media-now.co.uk 

07963 330774 

www.greenscapemag.co.uk 

Green roof manufacturers, installers and enthusiasts from around the 

world came together to celebrate World Green Roof Day on June 6th 2021. 

Building on the success of the launch event in 2020, organisers say the 

day attracted greater global involvement, with individuals from as far-afield as 

Malaysia, the Faroe Islands and Mumbai getting involved using the #WGRD2021. 

Whilst #WGRD2021 still took place largely online, it is hoped that the 2022 event will 

involve more face-to-face and live interaction. Organiser Chris Bridgman told us: “We 

hope to make next year’s event more interactive, with a range of opportunities for 

people to engage with green roofs, from taking part in rooftop tours, to attending 

workshops.” Read more on this year’s event on page 12. 

World Green Roof Day was the perfect platform for GRO to officially launch the updated 

version of the GRO Green Roof Code, and we provide a breakdown of the key points and 

additions to the latest version for users to make note of on page 10 of this issue. 

Sika Ltd. also used the event to promote its new green roofing range, and in this issue we 

take a closer look at the new offering, as well as some key installation tips on page 28. 

Elsewhere in this issue, Maggie Fennell of Boningale Ltd. provides planting and 

maintenance advice as she dispels our latest green roof myth (page 14); we hear about 

Green-tech’s irrigation solution for a London rooftop planting scheme (page 30); and 

take a look at Polypipe’s important blue-green roof project in Manchester (page 34). 

So read on for all this and much, much more! 

Front cover image is courtesy of Sika Ltd. Read 

about the manufacturer’s new green roofing 

range on page 28 

GREENSCAPE 

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CONTRIBUTORS TO THIS ISSUE... 

p18 

Green Talk: 

Q&A 

Keith Hills, MD 

of ECO Green 

Roofs is in the 

hot seat! 

p24 

Academic 

Corner 

Dr Tom Young of 

STRI Group digs 

into the detail of 

green systems! 

p40 

Navigating the 

‘solar coaster’ 

Christelle 

Barnes of 

SolarEdge talks 

all things solar. 

Keith discusses his career so far, past 

projects, challenges and opportunities 

within green infrastructure, plus why 

our reconnection with nature is great 

news for the sector. 

Find out more on page 18. 

In the first instalment of his new, 

regular column, Dr Tom looks at 

biosolar roofs in more detail, focusing 

on their key benefits and installation 

considerations. 

Find out more on page 24 

Christelle explains why the solar PV 

sector of today is drastically different 

to that of ten years ago, and why this 

presents a number of opportunities for 

those who want to do things right. 

Find out more on page 40 

www.greenscapemag.co.uk • GREENSCAPE SUMMER 2021 3

Contents 

NEWS 

06 Next stop sustainability 

Bridgman & Bridgman has installed 

green roofs on a number of bus 

stop shelters in Milton Keynes 

06 The British Association of 

Landscape Industries has 

launched two new training courses 

08 Take a look at GRO’s work 

with RBG Kew to help the public 

reconnect with nature 

GREEN ROOFS 

10 Cracking the Green Roof Code 

We take a closer look at the latest 

updates to the GRO Code 

12 The increased interaction with 

#WGRD2021 is a great sign for the 

green roof sector... 

22 Dr Anna Zakrisson of Green 

Roof Diagnostics talks all things 

stormwater management 

32 The shape, design and location 

of this green roof project produced 

a number of challenges for Sika and 

Progressive Systems 

4 GREENSCAPE SUMMER 2021 • www.greenscapemag.co.uk

GREENSCAPE 

SOLAR PV 

36 What are the prospects for 

the solar PV retrofit market? 

Marley’s Stuart Nicholson and Stuart 

Elmes of Viridian Solar give their 

take on things... 

40 Greenscape caught up with 

Christelle Barnes, of SolarEdge, to 

discuss the ups and downs of the 

‘solar coaster’ and why she’s positive 

for the sector moving forward 

REGULARS 

14 Mythbusters Boningale Ltd’s 

Maggie Fennell talks planting and 

maintenance as she dispels our 

latest green roof myth 

18 ECO Green Roofs’ Keith Hills 

tackles our Q&A and explains why 

the public’s reconnection to nature 

is a great sign for the sector 

24 Dr Tom Young of GRO and STRI 

Group looks at biosolar roofs in 

more detail in his first Academic 

Corner column 


News 

GREENSCAPE 

TRAINING AND GAINING 

The British Association of Landscape 

Industries has launched two new 

training courses at Supervisor and 

Manager level, to join its popular 

Register of Land-based Operations 

(ROLO) Operative level course. 

It says the new courses will enable 

industry Supervisors and Managers 

to receive the appropriate level of 

health and safety training and apply 

for their LISS/CSCS cards. 

The Supervisor and Manager level 

courses have been developed by 

the Association to meet the training 

needs of the land-based sector. They 

are fully supported and approved by 

CITB and Build UK as equivalent to 

the CITB SSSTS and SMSTS courses. 

Wayne Grills, Chief Executive of the 

British Association of Landscape 

Industries, said: “Over the years our 

provider network has been delivering 

ROLO training to the industry, we 

have seen standards across sites 

consistently improving. In response 

to the increasing call for higher level 

courses from businesses who are 

seeing how useful ROLO training is, 

we have developed these two brand 

new courses to continue our legacy 

of improving standards.” 

For more information, please visit 

www.bali.org.uk/ROLO 

NEXT STOP SUSTAINABILITY! 

Bridgman & Bridgman, working 

with living roof designer Dusty 

Gedge of the Green Infrastructure 

Consultancy, have installed what 

is described as “a pioneering new 

green roof system” to 15 bus stop 

shelters for Milton Keynes Council. 

Considered to be carbon negative, 

it is said to be the first time this 

approach has been undertaken on 

such a scale anywhere in the world. 

The size of the shelters in Milton 

Keynes range between 8-16m 2 . 

Each of the 8m2 bus stop shelter 

green roofs is constructed from 

312kg of recycled waste plastic – the 

equivalent of 18,720 carrier bags 

– and delivers 480kg of direct CO 2 

emissions savings via the use of endof-life 

recycled plastics. 

In total, the companies involved 

say construction of the new green 

roof bus stop shelters has recycled 

over 5 tonnes of waste plastic – the 

equivalent of 332,280 carrier bags – 

and delivered over 8 tonnes of direct 

CO 2 emissions savings. The first 

green roof on a bus shelter in Milton 

Keynes was installed by Bridgman 

& Bridgman in 2016 as part of a 

Britain in Bloom initiative. Since 

then, cities around the world have 

been greening bus stop shelters, 

including 316 shelters in Utrecht, The 

Netherlands. The city of Hamburg, 

Germany, has committed to 4,200 

greened shelters, sometimes 

referred to as Bug or Bee Stops. 

UK green roof bus shelter locations 

include Manchester, Newcastle, 

Leicester and Brighton. 

Milton Keynes Council has also 

worked with contractor Axiom to 

green a further fifteen bus shelter 

roofs using a modular green roof 

system. Cllr Jenny Wilson-Marklew, 

Cabinet Member for Climate and 

Sustainability at MK Council, said: 

“As well as providing a habitat for 

many small pollinating creatures, 

and improving biodiversity, the green 

roofs will be a great signal for MK’s 

green and sustainable ambitions.” 

www.bridgmanlandscapes.co.uk 


SIKA NOW OFFERS A COMPLETE 

GREEN ROOFING SYSTEM 

WITH ROOTS LIKE OURS, IT WAS 

THE NEXT NATURAL STEP 

Building on our reputation in roofing, Sika’s complete 

green roofing system provides many sustainable 

benefits. And on one project, it has even provided 

a grazing area for a flock of Dutch Spotted Sheep, 

who help reduce maintenance costs. 

Sika’s complete green roofs help to manage storm 

water, improve the building’s thermal performance 

and enhance biodiversity in nature. 

SikaRoof ® 

Wildflower 

Blanket UK 

SikaRoof ® 

Substrate 

Bio-diverse UK 

SikaRoof ® 

Rigid Drainage 

Layer 20 UK 

SikaRoof ® 

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WOULD YOU LIKE TO KNOW MORE? 

Email enquiries@uk.sika.com 

Visit www.sika.co.uk/greenroof

News 

SEMPERGREEN EXPANDS UK 

STOCK LOCATIONS 

The Sempergreen Group has 

expanded its stock locations with a 

UK HUB near Manchester. 

From this new location, Sempergreen 

can deliver its quality vegetation 

blankets quickly from local stock, for 

both large and small orders. 

This location will stock various 

vegetation blankets for green roofs, 

including the most commonly used 

Sedum-mix blanket, but also the 

Wildflower blanket for biodiverse roofs. 

Sempergreen says opening this new 

location fits with its mission and 

vision to contribute to a green and 

livable world and to counteract the 

consequences of climate change 

and environmental pollution. To keep 

its ecological footprint as small as 

possible, Sempergreen operates from 

local nurseries as much as possible. 

The Sempergreen Sedum blankets 

can be applied for both regular 

and lightweight roofing solutions. 

Sempergreen says it has also 

developed the perfect solution 

specifically for steeply pitched roofs. 

Contact Nicola Leyland (below) via 

nicola.leyland@sempergreen.com for 

further info on Sempergreen products. 

www.sempergreen.com 

GRO’S GREEN TEAM AT KEW 

Members of the Green Roof 

Organisation (GRO) have worked 

together to install green roofs on 20 

play structures at the Royal Botanic 

Gardens (RBG) Kew, which is on 

a mission to encourage people to 

reconnect with the incredible nature 

that surrounds them after over a year 

spent largely indoors. 

This summer, the leading plant 

institute and UNESCO World Heritage 

site is delighted to invite visitors on a 

journey to uncover the Secret World 

of Plants, supported by Starling Bank. 

At the heart of the festival are six 

‘plantscapes’ – large-scale, immersive 

biomes representing contrasting 

landscapes found across the UK, 

but rarely experienced in such vivid 

detail. Each landscape – sand dune; 

moorland; marsh and meadow; 

hedgerow; woodland; and urban 

– is inspired by the UK’s priority 

habitats in the Biodiversity Action 

Plan: an internationally recognised 

programme addressing threatened 

species and habitats. Visitors are 

invited to literally place themselves 

within these monumental landscapes 

via playful head-holes, and get a 

new, unique glimpse into these 

incredible, biodiverse and threatened 

UK landscapes designed by Seattlebased 

artist Vaughn Bell. 

The RBG Kew says it is passionate 

about increasing public 

understanding of plants and the 

important role they play in human 

life. With over 350 scientists and 

work spanning over 100 countries, 

RBG Kew says it is leading the way 

in discovering and describing new 

plant species, researching their uses, 

assessing their risk of extinction, 

and conserving them for future 

generations. It points out that plants 

are our life support – they provide 

us with food, materials, medicine, 

and more – and RBG Kew has one 

of the largest and most important 

collections in the world. Contributing 

to the ‘plantscapes’, the 20 colourful 

structures include several pitched, 

sedum and wildflower, biodiverse, 

edible and turf roofs that enable 

children to discover that rooftops of 

any size can be living and encourage 

more greening in urban environments. 

Through initial contact from RBG Kew 

with GRO member Bauder, the project 

was led by Mike Cottage of The Urban 

Greening Company with materials 

generously supplied by Bauder, 

Harrowden Turf, Sempergreen and 

Optigrun. Representatives from GRO 

member organisations then came 

together, including Radmat, Pritchard 

& Pritchard, Eco Green Roofs, The 

Urban Greening Company and 

Bridgman & Bridgman to install the 

green roofs over three days. 

www.greenrooforganisation.org 


GREENSCAPE 

LONG-TERM SOLAR 

AMBITIONS PRAISED 

Solar Energy UK has praised the 

Climate Change Committee’s call for 

“long-term ambition” around solar 

and other renewables, as a means to 

reducing greenhouse gas emissions 

in line with the Government’s 

commitment to achieving a net zero 

economy by 2050. 

The trade association says the 

report points to analysis from the 

International Renewable Energy 

Agency that highlights some 

solar generation sources as now 

producing the cheapest electricity 

in history, and draws parallels with 

the International Energy Agency’s 

recommendation for a rapid buildout 

of renewables, particularly solar 

and wind, in order to deliver a net 

zero power sector by 2035. The 

CCC’s recommendations specify that 

renewables need to meet 70% of the 

UK’s electricity demand by 2035. 

Chris Hewett (below), Solar Energy 

UK Chief Executive, said: “Green 

NGOs, energy trade bodies, and now 

the Climate Change Committee are 

all calling for the Government to 

be ambitious around solar energy. 

We need to deploy this affordable, 

proven technology as fast as possible 

to ensure we can meet the clean 

power needs of a net zero economy. 

We will go faster with some timely 

interventions from Government.” 

www.solarenergyuk.org 

SUSTAINABILITY AWARD FOR FLEX-R’S CWM MAWR PROJECT 

Flex-R is celebrating after its award-winning project Cwm Mawr came out top in the 

‘Best Sustainability’ category at the 2021 SPRA Awards. 

Flex-R received the award for its work with contractor Randell and Janes Roofing on a 

distinctive project which sits in an area designed as an SSSI (Site of Special Scientific 

Interest). Cwm Mawr, in the heart of the Welsh National Park, has been designed by 

architects Kinver Kreations as a low impact dwelling that blends seamlessly within its 

surroundings. The roof features a large, curved form to echo the surrounding hillside 

which has been completed with a green roof. Large windows have also been added to 

capture the stunning coastal views. 

Requiring a membrane which would be buried beneath a green roof, the architects 

needed assurances that the installation would be professional, accurate and backed 

by robust warranties. 

Tom Kinver, owner of Kinver Kreations, explained: “We have worked with Flex-R 

and Randell and Janes Roofing on previous projects and having them again on this 

difficult project was so important to us. The experience of the contractors, their 

extensive knowledge of the product and the support from Flex-R made every stage of 

the project so easy for us. 

“Flex-R’s specification team worked closely with us and the roofing contractor 

throughout the project. They advised on the correct specification during the tender 

stage and recommended their RubberBond FleeceBack EPDM which offers superior 

protection and long-term durability. Most importantly for this project, it has been BBA 

certified as a waterproofing membrane suitable for green roofs and resistant to root 

penetration.” 

Due to the sensitivity of the site, which contains rare plants and flowers of particular 

interest to science, Flex-R worked with the roofing contractors to carefully plan the 

installation and overcome any challenges. This even meant that no heavy machinery 

was allowed on the build and all the materials had to be carried by hand down a quarter 

of a mile narrow track! Danny Cole, Sales Director at Flex-R, said: “I am immensely proud 

of the hard work by our contractor Randell and Janes Roofing and the team at Flex-R 

on this project. Cwm Mawr, with its unique RubberBond FleeceBack EPDM membrane 

topped with a green roof, is a great achievement by everyone involved.” 

www.flex-r.co.uk 


GRO CODE UPDATED 

CRACKING THE 

GREEN ROOF CODE 

The 2021 edition of the GRO Green Roof Code of Best Practice 

continues to hold true to its original values, but also includes 

guidance on blue roofs, biosolar roofs and modular green 

roofs. Below, the experts at GRO explain more about this 

important document… 

To find out more about 

joining GRO email: 

membership@green 

rooforganisation.org 

www.greenrooforganisation.org 

Tweet: @RoofGro 

The latest instalment of the GRO 

Code was launched on 10th June 

2021. It’s the third edition and a 

special anniversary edition of the GRO 

Green Roof Code of Best Practice, which 

was first published in 2011 by the then 

newly established GRO ‘Green Roof 

Organisation’. 

GRO and the Code have gone from 

strength to strength since its beginnings 

as a voluntary organisation of a few 

enthusiastic contributors under the 

keen eye of former NFRC CEO Ray 

Horwood, and GRO is now a Trade 

Association registered with Companies 

House. 

The 10 year Anniversary edition of 

the GRO Code continues to hold 

true to the original values of making 

green roof technology accessible and 

guiding best practice. The original 

Code was the result of an EU funded 

project at the Green Roof Centre, 

University of Sheffield. As a result it was 

always going to be free to access and 

therefore would never be a Standard. 

The Green Roof Centre took advice 

from livingroofs.org and all the other 

GRO members to create a document 

that demystified and established 

performance criteria to specify, design, 

install and maintain natural-based living 

roofs. 

The 2021 edition of the Code has 

welcomed the inclusion of the 

increasingly popular and rapidly 

developing technology of blue roofs, 

biosolar roofs and modular green roofs. 

Who is the GRO 

Code for? 

Green roofs are not ‘rocket 

science’ but they are easy 

to get wrong in a surprising 

number of ways! Therefore, 

the language of the Code, 

and the comprehensive 

glossary, are intended to 

make the technology of 

green roofs as accessible 

as possible. The guidance 

held within the Code is 

as applicable to an Architect planning 

a 10,000m 2 accommodation block, 

to a homeowner considering a 20m 2 

extension or garden office. 

When should you use the 

GRO Code? 

It is best to consult the Code at the 

earliest possible stage in a design or 

project plan. Green roofs may be the 

last part of the external structure to be 

applied, but they have an impact on the 

very structure of the building and even 

the foundations. The benefits of green 

roofs can be found in the Code, these 

highlight where costs gained for the extra 

loading can be offset by water retention 

and biodiversity net gain calculations. 

It is also necessary to consider 

ongoing green roof maintenance at 

the earliest stage. A green roof is an 

investment, but it will only perform 

to its full potential if it is correctly 

maintained. For example, a newly 

installed green roof with pre-grown 

flowering turf will 

need watering for 

the first few weeks 

and after prolonged 

dry spells. With this 

in mind, is there a 

water supply? Does 

it have any pressure? 

These things are 

easy to change on 

paper, but difficult and 

potentially expensive 

during construction. 

Where should the GRO Code 

be used? 

The UK has a unique and sometimes 

frustrating climate. For such a small 

country it has a peculiar range of very 

dry areas, very wet areas, very windy 

areas and lots of areas that have a 

blend of these conditions. The Code has 

drawn from the vast experience of its 

members to produce guidelines that will 

perform well in most of the regions of 

the UK. If the site you are considering 

has additional special environmental 

conditions, a green roof specialist should 

be consulted. The Anniversary GRO 

Code is free and available to everyone 

in the UK and beyond, although it is not 

specifically designed for climates outside 

the UK and Ireland. 

Further updates and extensions to the 

Code will be developed by the GRO 

board and membership, led by the 

Technical Committee. 


Beneath your green roof you need waterproofing 

and thermal insulation that are BBA certified for 

the application. 

• Extensive sedum, wildflower 

and biodiverse green roofs 

• Blue roofs 

• Thermal insulation 

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www.greenroof.radmat.com 

Tel: 01858 410372 Email: TechServices@radmat.com

#WGRD2021 REVIEW 

INCREASED INTERACTION IS 

GREAT NEWS FOR SECTOR 

With ministers and government bodies getting involved, 

increased interaction and some big announcements from those 

operating in the industry, #WGRD2021 highlighted a better 

understanding of green roofs and a bright future for the sector. 

Building on the success of its 

launch in 2020, the organisers 

of Word Green Roof Day have 

announced this year’s event was bigger 

and better, with even more engagement 

from new countries, including 

Argentina, Ghana, Nigeria, Malaysia, 

Singapore, Vietnam, Kuwait, Lithuania 

and Albania. The event also even 

welcomed interaction and green roofs 

from Mumbai and the Faroe Islands! 

Using #WGRD2021, companies and 

individuals shared images and videos of 

green roofs and rooftop gardens from 

around the globe. Standout interaction 

included Emporio Armani celebrating 

funding a green roof on a children’s 

hospice in the UK, new telephone 

booths with green roofs being launched 

in Austria, and an open rooftop tour 

was hosted in Rotterdam! 

In addition to celebrating green roofs, 

some used this dedicated occasion 

to officially launch new products 

and initiatives, including the 2021 

Anniversary Edition of the GRO Code 

in the UK; Sika launching a brand-new 

green roof product range (see page 

28); and a new eLearning Green Roof 

training course from Lantra (UK) 

launching. 

Future plans, some of them extremely 

grand and highlighting the scale of 

potential projects within the green 

infrastructure sector, were also revealed 

on the day, with The Netherlands 

announcing plans to build accessible 

roof gardens at high altitude, connected 

by air bridges, by 2025! Announcing 

this huge project, a statement was 

released on #WGRD2021 explaining that 

the organisations ROEF and Rooftop 

Revolution signed a “green alliance 

on top of a sustainable roof”, with the 

“roof activists” aiming to “strengthen 

each other in making even more green 

metres on our roofs”. Alexander van der 

Meer, co-founder ROEF explained: “We 

want to launch bigger initiatives with 

lasting impact, such as the creation of a 

roof park. For this we need an activating 

knowledge partner, and that is Rooftop 

Revolution.” 

Jan Henk Tigelaar, Director of 

Rooftop Revolution, also touched on 

the importance of collaboration and 

“joining hands”, when discussing the 

huge rooftop park at high altitude 

project: “ROEF’s experience and 

network gives us the space to push our 

boundaries in the field of awareness 

and activation.” 

Further evidence of the impact of 

#WGRD2021 and the increased focus on 

greening within cities was highlighted 

by the news that the global event was 

endorsed by the Austrian Environment 

Minister and the Welsh Government 

Minister for Climate Change; organisers 

say it also received the support of the 

United States Environmental Protection 

Agency. 

Further evidence was provided by the 

news that in the days following the 

event, the city of Milan, Italy, announced 

it will map all of its existing green roofs 

and walls. 

Chris Bridgman, of Bridgman & 

Bridgman, who launched World 


Green Roof Day alongside Green 

Infrastructure Professional and 

Founder of LivingRoofs.org, Dusty 

Gedge, explained that the increased 

reach and support of this year’s event 

was clear evidence of the greater 

understanding of the important role 

of green roofs, and the impact they 

will have on the built environment 

moving forward: “The wider reach 

of this year’s World Green Roof Day 

in terms of global engagement and 

variety of support far exceeded our 

expectations. There is growing support 

and understanding of the green roof 

sector and this was particularly evident 

when the Day received endorsement 

from Environment and Climate Change 

Ministers, as well as government 

bodies.” 

Chris is also pleased with the way 

#WGRD2021 has established itself as a 

key date for those within the industry, 

and explained that plans are well 

underway for more live interaction with 

green roofs – alongside online activity 

– for #WGRD2022, as Covid 

restrictions are hopefully 

relaxed: “Within the 

sector, World Green 

Roof Day has become 

a key focal point for 

suppliers and related 

organisations to 

come together to 

promote the benefits 

of green roofs and 

celebrate exemplar 

projects. 

“We hope to make next year’s event 

more interactive, with a range of 

opportunities for people to engage with 

green roofs – from taking part in rooftop 

tours, to attending workshops. We’ve 

been able to cultivate a strong following 

online and we are confident that we 

can capitalise on this as economies, and 

countries, open up again.” 

Find out more about 

World Green Roof Day 

www.worldgreenroofday.com 

@WGRD2021 

Images top to bottom. Jan Henk Tigelaar, 

Director of Rooftop Revolution (left) 

and Alexander van der Meer, co-founder 

ROEF, signed a “green alliance on top 

of a sustainable roof”; @urbanscapes - 

Amsterdam; Sika launched a new green roof 

range on #WGRD2021 – find out more on 

page 28. Further images from #WGRD2021 

available at www.greenscapemag.co.uk 


GREEN ROOFS MYTHBUSTERS 

MYTH: YOU CAN ONLY USE SEDUMS OR 

WILDFLOWERS ON EXTENSIVE GREEN ROOFS 

Maggie Fennell, of Boningale Ltd, gives her thoughts on this misplaced belief regarding planting 

on extensive green roofs, and outlines some of the different species which can be used, as well 

as the maintenance considerations which must be taken into account... 

Extensive green roofs are 

traditionally dominated by 

sedums for their extreme 

drought tolerance, or wildflowers 

chosen for biodiversity support and 

preference for low nutrient substrate. 

These survival skills make them natural 

candidates to cope with extreme 

weather conditions and the harsh 

growing environment of a rooftop. 

Low-growing sedums are often chosen 

to survive on shallow substrate depths 

and can provide fairly uniform winter 

cover. Wildflowers are mostly deciduous 

and create big bursts of flowers and a 

longer display of colour, with greater 

provision of nectar and some reaching 

a height of half a metre or more. This 

variety of plant forms and 

flower types is great for 

wildlife, and even once 

they have finished 

flowering and died 

back they provide 

valuable resource 

to insects and the 

local ecosystem. 

The removal of dead 

material should be 

considered at an early 

stage of development to 

ensure there is adequate access 

to bring excess biomass down from the 

roof, and scheduled in accordance with 

biodiversity objectives – refer to section 

5 of the GRO code for more details. 

However, dispelling the myth mentioned 

earlier, there are many more plant 

communities that can thrive in these 

conditions, particularly when you have 

the full 150mm substrate depth to 

allow for extra 

root growth 

and storage of 

water that will be 

accessible to the 

plants. These may 

be particularly useful 

to consider for extensive 

roofs that are overlooked, or 

those with challenging limitations 

for removing excess plant material 

but requiring a varied plant range for 

biodiversity and aesthetic performance. 

Coastal, alpine and steppe/prairie 

ranges that can offer a variety of lowgrowing, 

evergreen or semi-evergreen 

plants with a wide variety of forms and 

flowering seasons would fit the bill – as 

long as they are hardy, drought-tolerant 

and happy with low nutrient availability. 

Look for plants with silvery, hairy or 

waxy leaves, dwarf cultivars and a long 

flowering season. Low-growing varieties 

might provide great pollinator support 

with less requirement for material 

removal and maintenance, and plants 

such as small ferns could be helpful 

in shady areas. The RHS gives further 

guidance on optimising biodiversity 

support when using non-native plants, 

such as avoiding double flower forms. 

Bulbs can also be a great, economical 

way to extend the flowering season. 

Continued on page 16 >>> 


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>>> Continued from page 14 

When putting together a plant mix, 

think about how the community might 

develop over time. A range of different 

plants will react differently to extreme 

weather conditions providing greater 

resilience. It is also possible for some 

species to gradually disappear over 

time or be crowded out by vigorous 

neighbours, which may only become 

apparent over several years. 

The maintenance planning should 

consider whether the emerging plant 

community is still robust enough to 

withstand next year’s unknown weather 

cocktail, or if it has become dominated 

by one or two species that could 

become vulnerable and die back – as 

can be the case when invasive grasses 

take over. 

There are further important practical 

considerations for your plant palette 

including the lead times, growing 

season and commercial availability of 

material. A large range of perennials 

may be commercially available 

as 9cm pots rather than plugs – 

although plugs can also be available 

and are advantageous for quick 

root establishment. If 9cm (P9) 

plants are used there may be more 

displacement of substrate depending 

on planting density. 

Plants should be grown in a peat-free 

medium which supports the root 

integration into the substrate, as well 

as the wider responsibly-sourced 

growing media agenda. 

Many species can be requested to be 

grown to order in the required size in 

season from March – July. 

My ‘top tip’ for successful planting is 

to be clear on what performance you 

want and design accordingly. Readily 

available wildflowers and sedums 

could actually provide a more resilient 

community when combined rather 

than used separately. As we have ever 

greater need for clever optimisation 

of space and thrifty use of resources, 

we can employ the wide diversity of 

beautiful, multi-functional plant life to 

create the best nature-based solutions 

to support wildlife, people, and the 

planet. 

All Images courtesy of 

Boningale Ltd. 

Contact 

Boningale Ltd. 

www.boningale-greensky.co.uk 

Tweet: @boningaleroofs 

16 GREENSCAPE FEB 2021 • www.greenscapemag.co.uk

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GREEN TALK KEITH HILLS 

SECTOR WILL THRIVE THROUGH 

THE RECONNECTION TO NATURE 

Keith Hills, Managing Director of Eco Green Roofs, discusses his 

path into the green roof industry, his perspective on how the sector 

is performing, projects he’s been involved with, the challenges and 

opportunities on the horizon, and why our reconnection with nature 

is good news for the industry… 

GM: What was your path into 

construction and to your current 

position? 

KH: Initially, before entering the 

construction industry, I worked as 

a volatility market maker options 

and futures trader within the 

stock market for 12 years. After 

successfully supporting investment 

strategies for investors, I was dealt 

an opportunity within the green 

roof market. I have always been 

conscious of my impact on the 

environment and wanted to do 

something different. 

Understanding the environmental 

benefits green roofs can offer in 

mitigating urbanised flooding, 

alongside air purification and 

reducing urban heat island effect, 

to name a few, I made the decision 

to leave the commercially driven 

financial sector behind for a 

more environmentally focused 

opportunity. It has been the best 

career move I could have made. 

That move has resulted in the 

creation of Eco Green Roofs (EGR), 

which continues to grow year on 

year. Starting with a green roof 

offering, there has been further 

integration of sustainable solutions 

including blue roofs, solar, biosolar 

and recreational podiums/ 

roof gardens. I have 

been the Managing 

Director of the 

business since its 

creation in 2010. 

Tell us a bit about 

Eco Green Roofs... 

Biodiversity has played a huge part 

in the direction EGR has taken as a 

business. We offer a comprehensive 

biodiverse roof offering to suit 

specification whether it be 

meeting planning requirements 

or recommendation through an 

ecological report, to meet the 

environmental needs for each 

individual project. With mandatory 

requirements likely to be on the 

horizon from the Government, 

it was, and is, important both 

environmentally and with the 

potential compliance to regulation, 

that we offer a service from 

design and install to aftercare and 

maintenance. 

From this, and resulting 

from further governmental 

commitments made, we have 

created a biosolar offering, 

featuring all the benefits of a 

green and biodiverse roof, with 

the inclusion of PV panels, thereby 

cutting emissions and 

potentially contributing 

to zero carbon in new 

developments. 

EGR provides a 

complete design and 

collaborative project 

partnership through to 

after-care, including maintenance 

solutions for green envelope 

systems, green and biodiverse 

roofs, biosolar & PV, blue roofs, 

recreational podium/roof garden. 

With regards to green roofing, 

how is the sector performing? 

Due to the ongoing lobbying 

around the environmental benefits 

gained from green roofs, the sector 

continues to perform well, with 

green roofs being a mainstream 

option for creating healthy and 

more sustainable communities. 

On April 20th this year, the UK 

government set the world’s most 

ambitious climate change target into 

law; to reduce emissions by 78% by 

2035 compared to 1990 levels. 

Green roofs in particular contribute 

to atmospheric carbon dioxide 

reduction through their beneficial 

impact on energy consumption 

of buildings and sequestration of 


carbon in plants and substrates. 

A study by Bianchini and Hewage 

indicated that the annual air 

pollution reduction from a green 

roof will offset the emissions 

associated with its production 

after 13 to 32 years. 

What more should 

the government 

be doing to 

incentivise 

green roofs 

in towns and 

cities? 

Now, more than ever, 

designers/specifiers will 

seek support in creating green 

envelope buildings, to help contribute 

to a reduction in carbon emissions, 

of which green roofs and other 

sustainable roof solutions will play 

an integral part. The Government is 

looking at how it can place a price on 

carbon, as part of a ‘green recovery’ 

from the coronavirus pandemic. 

The Zero Carbon Campaign by 

Opinium has estimated that a 

carbon tax could raise £27bn a 

year by 2030, and could work by 

replacing or simplifying existing 

green levies on the industry. 

From an educational point of 

view, more could be done from 

thought-leaders within government, 

particularly community driven 

strategies, in educating decision 

makers of the benefits gained 

from incorporating green roofs. 

From an environmental point of 

view including water attenuation, 

air quality and biodiversity, it is the 

beneficial impact on people’s health 

and wellbeing. Research confirms 

Images show the Chimes Project in Westminster which EGR worked on. 

green open for sustainable roof solutions to 

space aids ensure that NBS specifications 

people’s 

are suitable for the changing 

mental and technologies of systems and 

physical health, products for those specifying. 

of which green 

The third key issue being discussed 

roofs/podiums can 

at GRO is the hierarchy risks when 

offer a solution, especially 

designing green roofs, to help better 

in urbanised areas where green 

inform those developing/creating 

open spaces are limited. 

specifications. 

You recently Chaired your first 

What are some of the more 

GRO Technical Meeting, what are 

common mistakes designers and 

some of the key issues you’re 

installers make when it comes to 

looking to tackle? 

green roof projects? 

The Building Safety Bill, with its 

From a design point of view, not 

purpose of putting in place new 

utilising a roof area to its maximum 

and enhanced regulatory regimes 

potential, in particular the inclusion 

for building safety, inclusive of 

of biodiverse enhancements. This 

enhancing fire safety. Fire continues 

is where a roof can incorporate 

to be pivotal in our discussions 

components such as log and sand 

at GRO, looking at each aspect 

piles, animal boxes and ephemeral 

including design, supply, install and 

pools to support biodiversity net gain. 

maintenance thereafter. 

A key consideration in installing a 

EGR has recently undergone fire 

green roof is maintenance, this is 

testing of its green and biodiverse 

not always factored into the design 

roof systems inclusive of a 

of a building, such as water outlets 

waterproofing build-up scenario, 

for irrigation systems. This is where 

offering Broof(t4) classification in 

it is important that designers look to 

line with Building Regulations, and 

the expertise of those that design, 

continues to endeavour to ensure 

supply and install green roofs at 

safe, sustainable solutions are 

early design stage. 

specified for the built environment. 


We are also looking at NBS clause/s 


GREEN TALK KEITH HILLS 


Installation wise, it is not necessarily 

a mistake, but often logistical 

challenges are faced when it 

comes to installing green roofs, 

in particular when materials need 

to be lifted to roof level. It is of 

paramount importance that teams 

are sequencing with other trades 

to ensure use of cranes and other 

machinery to safely deliver the 

green roof system components on 

to the roof, whilst meeting strict 

programme deadlines. 

If there was one roof that you 

could green anywhere in the UK, 

which one would it be? 

Emirates Stadium – Being an 

Arsenal fan I really wanted them to 

take this on. I visited the stadium, 

provided a quotation but they said 

they didn’t have the budget and 

ended up buying Granit Xhaka a 

week later…! 

Tell us about a project you’re 

proud to have been involved with… 

Tough one; from a prestige project 

point of view, Battersea Power 

Station. That being said, from an 

environmentally friendly feat, 

Chimes in Westminster was a 

fantastic project; not only did we 

install sedum roofs offering air 

purification, water attenuation 

(sedums have high water capacity) 

and natural habitats, these roofs 

could be overlooked by residents 

from the landscaped podium 

area with planters and evergreen 

shrubbery, supporting health and 

wellbeing. The project also included 

a blue roof system, to further 

support the mitigation of urbanised 

flooding by attenuating water, 

reducing the impact on the old 

London drainage system. Further 

greenery was incorporated 

within the communal courtyard, 

again giving residents an access 

to nature. This project should 

be considered a benchmark in 

which other projects in our inner 

cities should look to as a hybrid 

solution. 

What’s the biggest issue affecting 

the supply chain currently? 

The main issue affecting the 

supply chain is the lack of trained 

operatives to install the green roofs 

and other sustainable roof level 

system components, therefore 

impacting all those involved within 

the supply chain. It is not only the 

green roof industry, the roofing 

sector as a whole faces challenges 

with an ever-growing skills gap 

and shortage. An NFRC survey has 

shown that labour shortages was 

the second highest area of concern 

for roofing and cladding contractors 

in 2021. 

After what’s been a particularly 

challenging year, are there 

reasons to be positive within the 

green roof sector and the wider 

construction industry? 

Lockdown, for many of us, has 

facilitated a stronger connection 

with nature, due to not working 

in offices, venturing outside on 

work breaks and more time 

in evenings through the 

removal of commuting. 

In May 2020, 36% of 

people responding 

to the People and 

Nature Survey by Natural England 

said they were spending more time 

outside during the pandemic than 

before. This rose to 46% in July 

2020. 

Research carried out by Naturescot 

demonstrated the increase of those 

reacquainting themselves with 

nature, with many reporting that 

after spending time outdoors they 

felt that they had gained health and 

wellbeing benefits. It’s never been 

more important for not only the 

environment but also us as people 

to ensure there is no devastating 

loss to biodiversity, to ensure our 

natural world thrives alongside us, 

for us to enjoy. 

Green and biodiverse roofs 

will continue to thrive through 

the reconnection to nature, 

Government mandates for 

biodiversity, net zero carbon targets 

and reducing the impact of climate 

change. 

Contact 

Eco Green Roofs: 

Tel: 01277 355705 

www.ecogreenroofs.co.uk 

Tweet: @EcoGreenRoofs 

With regard to the construction 

industry, many companies 

have thrived in the pandemic 

due to funding placed via 

the Government to support 

stability in the UK’s economy. 

The construction industry has 

demonstrated resilience alongside 

being compliant to safe practices. 

It will continue to grow and 

shape, though with a heavier 

focus on sustainability as part of 

a green recovery from the 

pandemic. 

The full version of our 

interview with Keith 

is available at www. 

greenscapemag.co.uk 


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STORMWATER MANAGEMENT 

GREEN ROOF RETENTION 

VS. DETENTION 

Dr. Anna Zakrisson (below), of Green Roof Diagnostics, explains 

the difference between two of the industry’s most hotly 

debated concepts, with comment from Mike Wharton 

(inset right), of Complete Roofing Systems, on the importance 

of green and blue roofing. 

Traditional green roofs 

and retention 

Green roofs are 

excellent at 

reducing annual 

stormwater volumes. 

Up to around 60% of 

the annual precipitation 

can be retained by a highretention 

traditional green roof. This 

means that approximately 60% of the 

yearly rainfall never becomes runoff 

and never enters the canalisation. This 

water will never have to be cleared by 

a sewage treatment plant, a process 

requiring a lot of energy; this water also 

cools the cities through the process of 

evapotranspiration. 

This 60% represents retained 

water and leaves the roof through 

evapotranspiration: the combined 

processes of evaporation and 

transpiration. Retention is excellent at 

managing small storms: the 60% of 

the volume representing 80- 

90% of the total number 

of storm events. 

But what happens 

to the remaining 

40% of the volume 

representing 10-20% 

of the storm events? 

This is coincidentally 

the 40% that causes 

most damage to a city; 

intense and multiple-day 

rain events resulting in flooding 

and erosion. If you manage to slow 

down the outflow rates of the runoff, 

this damage will be prevented. 

Maximum allowable runoff 

rates 

Stormwater management 

can be summarised as such: 

“provide methods that 

reduce runoff rates from 

your property predictably 

and reliably to meet the 

maximum allowable rates set 

by the municipality.” Often these 

maximum allowable runoff rates 

are in the ballpark of 1-10L/s/ha for 

most European urban areas. Another 

commonly used term for this delay is 

“stormwater detention.” 

Many different types of at- and belowgrade 

stormwater tools can lower 

runoff rates by delaying the outflow of 

water e.g., stormwater tanks, cisterns, 

rain gardens, perforated pipes and 

many more. These methods are all 

space constraining and may thus 

cause some headaches for planners 

in many urban areas. However, you 

are required to show that the 

building is adequately 

protected against 

severe storm events, 

which is especially 

important now as a 

climate adaptation 

measure. 

The maximum 

allowable outflow 

rates must also be met 

under certain pre-defined 

conditions often referred to as 

a “design storm.” These statistical 

storms have a specific shape, describe 

a volume, and have a time factor. 

Commonly, your project must be able 

to deal with a so-called 100-year storm, 

or in more sensible terminology: a 

design storm that has a 1% probability 

of occurring in any given year based on 

past events. 

Available green roof detention 

(delay) solutions 

The outflow delay factor varies in a 

traditional green roof – for a dry roof 

it is several hours, worst case when it 

rained yesterday and today once again, 

we are talking about minutes, which is 

not nearly sufficient to meet the max. 

allowable outflow rates of a 100-year 

storm. 

In a typical green roof profile, the 

macropores never fill up to full capacity. 

Water simply falls out of these pores 

as they are too big to hold onto the 

water through capillary forces. Also, 

the drainage layer is an optimised 

water facilitator, not a restrictor, which 

is why traditional green roofs are not 

considered stormwater management 

tools in its fullest sense. However, there 

are several interesting detention/delay 

solutions on the market. 

With some blue-green roofs, you can 

circumvent the issue largely by simply 

storing most storms on the roof and 

using this water to irrigate the plants: 

little outflow and little water to slow 

down, ergo little detention. But even 

blue-green roofs release water when it 

rains 2-5 days in a row. Nonetheless, if 

you want to use it as a stormwater tool, 

it still needs to meet the requirement 

of managing the 100-year design 


Mike Wharton, Chief Executive, Complete Roofing 

Systems: “As the call for net zero carbon 2050 starts to 

get louder, we’re seeing more and more clients enquiring 

about green and blue roofs, as well as improved insulation. 

The ability to detain water is coming up more frequently 

as a client request too, and the constant improvement in 

technology will also help both the installation side and the 

ability for the industry to continue to push the agenda.” 

Complete Roofing Systems is a commercial roofing and cladding contractor. 

Find out more: www.completeroofingsystems.co.uk 

storm. Some types of blue-green roofs 

use orifice restrictions to release 

water at predictable outflow rates. 

For blue-green systems, you need 

a flat roof. Other solutions include 

Purple-Roof compliant systems that 

use a drainage fabric with internal 

turbulence to achieve reduced and 

predictable outflow rates also on 

sloped roofs. 

Sadly, it is a frequent misconception 

by many stormwater engineers that 

green roofs cannot be solid and reliable 

stormwater tools. Possibly because of 

a confusion of terminology between 

the green roof industry and the civil 

engineering world combined with a lack 

of solid stormwater modelling studies 

for green roofs. 

Many of the mathematical methods 

currently used in the industry are rough 

ballpark figures covering extremely 

narrow conditions that won’t satisfy 

stormwater engineers. This has most 

likely led to several great opportunities 

having been missed. 

Summary 

Contact Green 

Roof Diagnostics 

www.greenroofdiagnostics.com 

Tweet: @GRD_Research 

Retention cools our cities and 

reduces annual loads on our sewage 

treatment plants, and keeps our 

cities beautiful and green. Detention 

(delay) saves us from flooding 

damages and prevents horrible 

things like combined sewer overflows. 

Both processes are important 

and serve different purposes, and 

the latest blue-green and purple 

concepts can deliver both. 

www.greenscapemag.co.uk • GREENSCAPE SUMMER2021 23

ACADEMIC CORNER 

BIOSOLAR ROOFS: THE 

BENEFITS & KEY CONSIDERATIONS 

In the first instalment of his new, regular column, Dr Tom Young, GRO Board Member and 

Environment Systems Manager at STRI Group, looks at biosolar roofs in more detail... 

A 

huge amount of relevant 

research into green roofs 

has been conducted over the 

last 20 years. However, an issue with 

academic research is that it often does 

not filter through into the industry 

to help with improving design and 

maintenance of green roofs. In this 

regular column, I hope to provide easy 

to read summaries of hot topics in 

the green roof academic sector, and 

introduce readers to some academic 

research which is available. 

A common statement that everyone 

who has worked with green roofs has 

heard is: “I want a green roof, but I can’t 

have one as I want solar panels/ 

PV”. Now, having either of 

these technologies is 

commendable and 

will improve the 

sustainability 

credentials 

of a building. 

However, the 

answer back 

should always 

be: “well, why 

don’t you have 

both then?” Not 

only do you gain the 

benefits of both, but 

the two systems can actually 

complement and improve one another. 

Known as biosolar roofs, developers 

are increasingly becoming aware of 

the benefits of combining these two 

technologies. 

One of the first major studies into this 

area was conducted by Manfred Kohler 

in 2007 (Kohler 2007) which looked at 

two rooftop solar farms in Berlin; one 

with a bitumen roof and 

the other with a Sedum 

extensive green roof. 

This study provided 

initial results into 

an 8-year study and 

suggested a number of 

positive feedbacks from 

the two systems which 

have since been investigated 

by others in much more detail. 

Standard PV (photovoltaic or solar 

panels) panels appeared to produce 

1-15 % less electrical energy during 

the study period compared to green 

roof PV panels, and lead to an increase 

in plant diversity across the green 

roof. This was linked to the 

increase in ecological 

niches provided by 

the solar panels, 

with a decrease 

in surface air 

temperature 

by the green 

roof increasing 

PV panel 

efficiency. 

Subsequent 

studies have 

clarified the 

mechanisms described 

in the Kohler 2007 paper 

and helped to optimise the 

design of biosolar roofs: 

Benefit 

Increased PV output 

Key mechanisms 

Reduced air temperature on roof 

caused by evapotranspiration of 

vegetation, substrate heat sink, and 

Left: Dr Tom Young. Below: 

biosolar roof installation 

courtesy of Bauder. 

reduced albedo, leads 

to cooler PV panels. 

PV panels function 

more effectively at a 

lower temperature and 

therefore produce more 

energy. 

General power output improvements 

ranged between 1-8 %, with an average 

of 1-3 %. Some studies show negligible 

improvements (0.08-0.5%), due to 

position of solar panel, vegetation type 

and climate. 

Benefit 

Decreased air and roof temperature 


Reduced air and roof temperature can 

reduce requirement of air conditioning 

within building. Therefore, building 

energy requirements are reduced, 

allowing a greater amount of electricity 

to be used for other purposes or 

exported to the grid. 

Energy savings of 0-11 % have been 

modelled and observed for European 

green roofs, and up to 79% for roofs in 

Singapore. 

Benefit 

Improved plant diversity and resilience 


Increased range of shade patterns, 

which in turn causes range of 



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temperatures across roof surface. 

Uneven distribution of rainfall across 

the roof from solar panels, leading to 

wetter and dryer areas. 

Some plants enjoy different 

temperatures, and substrate moisture 

compared to others and thus 

differential plant communities start 

to form. Kohler 2007 observed an 

increase in plant diversity of 24 % on a 

PV roof compared to non PV roof. 

As a word of caution, some studies 

have found little impact upon species 

diversity (Schlinder 2018), although 

this may be due to the harsher 

Mediterranean climate the study roof 

was in. 

Most studies show that additional cost 

of green roof to a PV system has a 

rough payback period of between 10-20 

years depending on the climate and 

type of installation. More research is 

still needed to fully quantify pay back 

periods in different regions, in order 

to help prove the case for developers 

and building owners. In addition, more 

research is needed to understand 

the optimum design of biosolar roofs 

with key areas including vegetation 

composition and height 

of PV panel above 

roof. 

There is still 

no hard and 

fast rule for 

designing 

biosolar roofs, 

but some 

general design 

pointers are listed 

below: 

• May need additional 

walkways and access routes 

around PV panels 

• Green roof substrate can be used 

as ballast for the panel arrays. Panels 

can also be attached directly to 

drainage layers to prevent piercing the 

waterproof layer of the roof. 

• Vegetation maintenance is as 

important as ever, as uncontrolled 

growth can result in shading of panels. 

• Species selection during design stage 

is critical to ensure that correct types 

are selected. 

• Vegetation design can be much more 

ambitious, as PV panels 

provide multiple 

habitats across the 

roof in terms of 

shade, wind and 

water flow. 

• Correct 

height of PV 

panel above 

the roof is key 

to ensure cooling 

benefits are 

realised. 

GRO has recognised the 

increased need for guidance in 

this area, and has included biosolar 

general design points in the latest GRO 

Code. These will be built upon in further 

editions and as knowledge in this area 

increases. 

References available on request, or 

view at www.greenscapemag.co.uk 

Contact 

STRI Group 

Tel: 01274 565131 

www.strigroup.com 

E: tom.young@strigroup.com 

Tweet: @striturf_tomy / 

@striturf 

Images show biosolar roof projects. 

Courtesy of: Top Optigrun; Left Bauder; 

Centre two Bridgman & Bridgman; 

Above Optigrun. 


GREEN ROOF INSTALLATION 

HOW TO INSTALL SIKA’S NEW 

GREEN ROOF OFFERING 

With Sika having recently launched a new range of green roof 

systems, Richard Aldred MSc (pic right), UK Roofing Market 

Manager at Sika, offers advice on installation methodology and 

design considerations in this informative step-by-step guide. 

Presenting a myriad of benefits, 

green roofs are becoming ever 

more popular among specifiers 

looking to build for a sustainable future. 

In support of that, we’re thrilled to have 

recently launched our new Sika Green 

Roof systems. 

It’s a total package that allows specifiers 

to choose from a range of highperformance 

waterproofing systems 

that best fits their project’s needs 

– whether that’s hot melt structural 

waterproofing, reinforced bituminous 

membranes, single ply or cold-applied 

liquid membranes – all of which are 

compatible with Sika’s Green Roof 

systems. 

If you’re considering a green roof 

addition, but unsure about what’s 

involved from an installation 

perspective, read this six-step guide to 

installing a Sika Green Roof (applies to 

Sika’s standard products) 

Step 1 – Roof waterproofing and 

site checks 

Firstly, ensure the roof is complete and 

watertight. Check that the roof is a safe 

working environment (edge protection/ 

scaffold or mansafe system is in place) 

and have lifting equipment ready to 

lift materials to the roof securely. It is 

essential to ensure all other trades have 

finished working on the roof before 

starting, especially if the roof is a new 

build, making sure the roof is fully clear, 

as a loose screw or site debris can 

cause problems further down the line 

and mechanical damage normally isn’t 

covered under any roofing warranty. 

Step 2 – Protection fleece and 

Riverstone application 

Place the protection fleece roll onto the 

roof and lay over the waterproof layer in 

strips from one side to the other, ensuring 

there is an overlap of at least 100 mm for 

each strip of protection fleece, to prevent 

any gaps in the fleecing that may expose 

part of the waterproofing, and may risk 

subsequent damage to the waterproofing 

during the installation of the green roof. 

Step 3 – Aluminium edging 

installation 

The aluminium edging should be 

installed on roofs with a pitch to 

help retain the system on the roof. 

It is not required on flat roofs but is 

recommended for an aesthetic finish. 

The aluminium edging is placed 

underneath the Riverstone border – the 

weight of the Riverstone will hold the 

aluminium edging in place. Ensure that 

there are gaps in the aluminium to 

allow for drainage of excess water in the 

system. Retention edges can be glued 

together using a special aluminium 

adhesive. Make sure there is an overlap 

when adhering to avoid gaps in which 

the Riverstone and other parts of the 

border could fall off the roof. 

If a Riverstone border has been 

requested, place the sacks along the 

roof perimeter with a general spacing of 

1 bag per 800 mm. Slit bags open and 

hand place the pebbles evenly along 

the border at a width of 300 mm (or 

otherwise specified at the site location). 

Step 4.1 – Drainage board with 

filter fleece 

Sika’s drainage boards come in two 

varieties. A drainage sheet with a filter 

fleece already attached, and drainage 

rolls that require a separate roll of filter 

fleece. 

For the drainage sheets with filter 

fleece already attached, place the 

sheets across the roof surface with an 

overlap of at least 100mm where the 

excess filter fleece is located. This will 

prevent exposure of the waterproofing 

membrane and reduce the risk of 

any damage to it. Cut the sheets that 

overlap the 300mm Riverstone border, 

as well as around any protruding units 

attached to the roof to form neat 

edges. The adhered filter fleece is built 

to overlap to ensure substrate does not 

get into the drainage cups. 

Step 4.2 – Drainage board and 

separate filter fleece installation 

Roll out the drainage board onto the 

roof, creating a continuous drainage 

layer, cut the drainage board along the 

perimeter edges of the roof neatly. 

Leave a 300mm spacing between the 

drainage board and the edge of the roof 

for the Riverstone border. Where there 

are protruding skylights or other roof 

components, cut the drainage board up 

to and around the object to form a neat 

edge. Be careful not to damage the 

waterproofing layer. 

To apply with the filter fleece, follow the 

same method as the protection fleece. 

Allow for a minimum 100mm overlap to 


prevent the drainage board protection 

from being filled with substrate. 

Find out more about 

Sika’s green roof offering: 

Tel: 01707 394444 

www.sika.co.uk/greenroof 

E: enquiries@uk.sika.com 

Step 5 – Substrate installation 

Place substrate bags onto the roof over 

the filter fleece. This will prevent the 

fleece from being lifted by the wind and 

maximise homogeneity of the substrate 

depth across the roof. Cut the edge of 

the bags and spill the substrate evenly 

over the filter fleece. Use a rake to 

create an even spread of the substrate. 

Measure the depth of the substrate to 

check that the substrate is at a minimum 

depth of 50mm for sedum blanket 

and 100mm for wildflower blanket (if a 

deeper substrate is specified, measure to 

the indicated depth). 

If bulk bags are being used, lifting 

equipment will be needed to hang the 

bulk bags over the roof. You can either 

slit the bottom of the bag or shovel the 

material from the bag onto the roof 

evenly to the depth specified by the 

project. Great care must be considered 

when emptying bulk bags to prevent 

excessive loads of substrate onto one 

point of the roof, which could lead to 

damage to the roof systems if the weight 

exceeds the restrictions of the roof. 

Step 6 – vegetation installation 

Unroll the blankets on top of the 

substrate, butting each roll close to the 

other. Cut rolls at the roof perimeter 

and use extra pieces to complete the 

roof. Also cut parts where skylights 

protrude from the roof. Excess debris 

blanket and/or soil left after installation 

can be used to fill in any bare patches 

where the blanket system has 

deteriorated during transportation. 

Considerations 

Green roof systems include living 

products which must be installed 

on the day of delivery and watered 

immediately upon installation and 

for the first 12 weeks in situ. This is 

especially important during the Spring 

and Autumn period each year. For 

pitched roofs over 7.5 degrees, an 

irrigation system is recommended to be 

installed with the roof. 


CASE STUDY IRRIGATION 

STAYING WELL-WATERED 

ALL YEAR AROUND 

Contact 

Green-tech 

Tel: 01423 332100 

www.green-tech.co.uk 

Tweet: @Greentechltd 

Green-tech has provided an irrigation solution for a rooftop 

planting scheme at 80 Charlotte Street in Fitzrovia, London. 

80 Charlotte Street, in the 

exclusive Fitzrovia district 

of London, is a mixed-use 

development featuring an impressive 

line-up of greening measures, all helping 

to achieve Carbon Net Zero status. 

Having the kudos of being London’s 

first all-electric building, 80 Charlotte 

Street is rated BREEAM 2014 Excellent 

and is on track to achieve LEED 2009 

Gold, meaning that this cutting-edge 

building is expected to consume 25% 

less energy, and generate 34% lower 

greenhouse gas emissions than the 

average commercial building. This 

impressive green performance is 

achieved whilst retaining much of the 

existing structure and facades and 

combining it with new. 

One of the main goals for MAKE 

Architects, the building’s designers, was 

to engender a strong sense of wellbeing 

for the office workers, residents and 

public that use it. As part of this 

commitment, the design allowed the 

inclusion of numerous roof terraces, 

both private and shared for the offices 

and residents, offering dramatic views 

over Fitzrovia including the BT Tower. 

Green-tech were contacted by Barton 

Willmore landscape architects, with whom 

they have a long working relationship 

going back nearly ten years, to quote for 

irrigation for the many planters that were 

required on two of the external terraces; 

part of a design developed by Piercy & 

Company Architects for a specific highend 

tenant fit-out. 

The most effective solution was to use 

Green-tech’s Mona tank system. This 

subterranean reservoir system irrigates 

the soil through capillary action, 

reducing watering frequency whilst at 

the same time aerating the soil. 

With sizes from 3 to 24 litres, the Mona 

tanks can either be used individually 

or linked together in line, for beds and 

longer runs. Each tank has two capillary 

legs that are back-filled with soil and 

reach down into the water inside the 

reservoir. Once filled via the filler pipe the 

tanks act as a reservoir, supplying water 

to the rooting soil via capillary action. 

As the water is taken up, the empty space 

is replaced by air through the filler pipe, 

acting as both irrigation and aeration. If 

the surrounding soil is damp, the tanks 

do nothing and the water is stored – once 

the soil dries out, the water is taken up 

by capillary action into the soil, keeping it 

moist. 

Over 200 tanks were 

supplied to the 

Landscape 

Contractor Oasis 

Plants for the 

terrace planters, 

ensuring that the 

plants are kept 

well irrigated all 

year round. 

Commenting on 

landscape supplier 

Green-tech, a spokesperson 

from Barton Willmore Landscape 

Architects explained: “We have worked 

with Green-tech for many years now, 

and they can always be relied on not 

only to help out at the front end with 

specification and cost proposals, but also 

provide a reliable service when it comes 

to supply.” 

Planting at the 

Charlotte Street roof 

garden courtesy of 

Barton Willmore. 

Green-tech’s Specification 

Advisor Alasdair Innes added: 

“We have a great relationship with 

Barton Willmore, and it is particularly 

exciting to be involved on a project with 

such impressive green credentials. The 

Mona tanks do their job so well, I have 

no doubt that they will keep the terraces 

green and healthy for many years to 

come.” 


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GREEN ROOF PROJECT FOCUS 

PLAIN SAILING FOR THE LINER 

GREEN ROOF PROJECT 

We take a look at the roofing element of The Liner luxury 

apartment project, where the shape and exposed location 

posed some interesting challenges for Sika’s technical team 

and contractor Progressive Systems... 

The Liner, a nautical-inspired 

£35m residential new-build 

in Falmouth, presented a 

compelling roofing challenge. Exeterbased 

roofing contractor, Progressive 

Systems, assisted by Sika, took on 

the task, installing a roof to withstand 

the harsh seaside conditions with an 

immaculate finish. 

Boasting panoramic views of 

Gyllyngvase Beach, this latest 

development by Acorn Blue consisting 

of 52 luxury residential apartments was 

designed by Poynton Bradbury Wynter 

Cole Architects. Far from a conventional 

footprint and façade, the six-storey ‘V’ 

shaped building echoes the bow and 

upper decks of an ocean liner, with a 

‘bridge’ containing penthouses on the top. 

The curved roofline is designed to 

resemble the ocean waves. A podium 

component comprising additional 

residential apartments, commercial and 

retail spaces was also required. 

Progressive Systems and Sika were 

selected for the job thanks to their 

outstanding work on The Dunes in 

Perranporth, a prior beachfront project 

with Acorn Blue. Testament to this, 

said project won the Single Ply Roofing 

category in 2019’s NFRC UK Roofing 

Awards. 

Project details: 

The Liner, Falmouth 

Contractor: Progressive Systems 

Roofing client: Acorn Blue (part of 

Acorn Property Group) 

Size: 2300m 2 

Products: Sika Sarnafil G410 18EL 

PVC Single Ply Waterproofing 

Membrane, Sarnavap 5000E SA 

Vapour Control Layer, Sarnafil 

Primer 610, Sarnatherm ‘G’ 

insulation, Sikalastic 625, Sarnafil 

G445-13 PVC Protection Sheet, Sika 

Green Roof System. 

Range of roofs 

The scope of the roofing works included 

the penthouse roof and balconies, 

winged roofs, garden apartments, 

roofs for the commercial units, plant 

room, paddleboard store and podium 

roof, totalling an area of approximately 

2,300m 2 . 


Contact 

Sika 

Tel: 01707 394444 

www.sika.co.uk/roofing 

E: enquiries@uk.sika.com 

Tweet: @SikaLimited 

As the building would be exposed to 

the coastal elements, Acorn Blue was 

looking for a robust roofing system that 

would withstand the Cornish winters. 

Sika’s technical experts helped to create 

a robust specification using a range of 

durable roofing systems, guaranteed to 

stand the test of time. 

This included a fully adhered single ply 

membrane Sika Sarnafil G410 18ELF, 

Sika Liquid Plastics Sikalastic 625 for 

the balconies and podium, and a Sika 

Green Roof system, to best suit the 

various requirements of each area. 

Sika conducted thorough wind uplift 

calculations to reassure the architect 

and client that this type of system 

would withstand the high winds. 

On top of this, Progressive designed a 

bespoke galvanised “c” channel detail to 

match the sweeping curvature of the roof 

design. A time-consuming challenge, but 

one that ensured that no direct winds 

would impact on the edges of the roofing 

system, giving further peace of mind. 

Sika Green Roof was specified for the 

garden apartments, commercial units 

and first floor podium roof. These 

roofs are the most bespoke part of the 

building because of the curvature and 

multiple pitches that were built on each 

individual roof (created in structural 

steel with timber joists and a multi-cross 

weaved layered plywood deck). Due 

to the exposed coastal environment, 

specific coastal plants were chosen 

to withstand the conditions, increase 

biodiversity and give a stunning visual 

impact. 

Creating the paddleboard shape for 

the penthouse roof took time and 

expertise. Close attention had to be 

paid to ensure the correct curvature 

was being created. However, despite the 

irregular shapes, all roof junctions and 

upstand details were kept as simple as 

possible to reduce the potential for any 

further issues. Keeping these “typical” 

details simple was key to the project 

running smoothly. 

Images show work by Progressive Systems 

and Sika at The Liner, a nautical-inspired 

residential new-build project in Flamouth. 

Steve Kerswell, from Progressive 

Systems, said: “From inception through 

to project completion, Sika was in close 

contact with us. They were always 

happy to discuss and resolve any design 

and specification queries. We found 

the field technicians’ weekly site visit 

both useful and informative for both 

us and our client, who took confidence 

that another set of eyes were checking 

the quality of the roofs’ install and 

detailing.” 

Thanks to the impressive workmanship 

of Progressive and the high quality 

finish of the Sika roofing systems, the 

final result is worthy of topping the very 

best in contemporary coastal living. 

Following the successful completion of 

The Liner project, Progressive and Sika 

have been invited to tender on further 

upcoming coastal projects. 


BLUE-GREEN ROOFS 

BLUE-GREEN ROOF SCENE 

IN MANCHESTER 

Polypipe Civils & Green Urbanisation’s blue-green roof 

installation at Bloc is said to be “a perfect example of the 

future workspaces of tomorrow, today”, with the innovative 

roof set to provide a climate resilient vision for Manchester. 

Work has been completed on 

the installation of a groundbreaking 

climate and water 

resilience research roof in the heart of 

Manchester. 

Sited on Bloc – a city centre workspace 

that has been transformed by 

Bruntwood Works as part of its £50m 

Pioneer redevelopment programme 

– the blue-green roof from Polypipe 

Civils & Green Urbanisation will help to 

develop a greater understanding of how 

new construction and data technologies 

can help cities and urban developments 

to mitigate the impact of climate 

change and population growth, while 

enhancing biodiversity. 

Over the next two years, the ‘smart’ 

blue-green roof, designed by 

environment management consultants 

EPG, part of the STRI Group, will allow 

United Utilities – which co-funded the 

development at Bloc – to assess how 

storing and re-using rainwater at roof 

level can reduce the volume of surface 

run-off entering its sewer network. As 

a result, it will help to lower the flood 

risk associated with the prolonged 

high-intensity storm events that are 

becoming increasingly frequent as the 

climate changes. 

Unlike conventional green roofs, which 

use a drainage layer to simply remove 

rainwater, the 525 sq m blue-green 

structure retrofitted to Bloc’s flat roof 

stores rainwater beneath the planted 

surface where it lands. Advanced 

passive irrigation components within 

the attenuation layer draw water up 

through the structure to the underside 

of the green roof substrate to support 

surface planting. 

The breakthrough technology protects 

green areas during periods of drought, 

reduces potable water demand during 

hot weather and enhances biodiversity 

by maintaining flora in optimum 

growing conditions. In the case of Bloc, 

planting has been specially selected 

by partners of the project, STRI, from 

local varieties to help attract pollinators 

and a particularly rare butterfly, the 

Manchester Argus. 

This net-zero re-use of water to sustain 

surface planting is a new approach to 

water management known as green 

urbanisation, and represents the next 

generation of sustainable drainage 

systems (SuDS). 

Nicholas Wright, Specification Business 

Development Director at Polypipe 

Civils & Green Urbanisation, said: “The 

two-year roof research programme at 

Bloc will demonstrate the full creative 

and multifunctional potential of green 

urbanisation, which represents the next 

generation of sustainable drainage 

systems. 

“By introducing integrated natural 

habitats across the urban landscape, 

we create healthier, more resilient 

communities that are highly carbon and 

energy efficient.” 

Sophie Tucker, United Utilities’ Area 

Engineering Manager, said: “As a 

company, we continue to explore 

innovative ways on how things can 


Contact Polypipe Civils 

& Green Urbanisation 

www.polypipe.com/ 

green-urbanisation 

Tweet: @PolypipeCivilGU 

be done differently, as we look at 

alternative methods to increase 

resilience in our sewer systems, away 

from simply building underground. 

As such, we’re heavily invested in 

learning more about urban assets 

that can deliver surface water 

separation and sustainable solutions 

which can make our regions more 

resilient to the long-term impact of 

climate change.” 

Bruntwood Works’ re-imagining of 

the 16-storey office block on Marble 

Street has introduced a raft of new 

workspaces, amenities and technology, 

and has a focus on biophilia to help 

improve wellbeing. As well as a twostorey 

living wall that provides oxygen 

and helps reduce noise levels, Polypipe 

Civils & Green Urbanisation’s blue-green 

roof installation has made Bloc the 

home of Manchester’s first wildflower 

roof. 

Andrew Cooke, Strategic Director at 

Bruntwood Works, added: “At Bloc, the 

latest project in our £50m Pioneer 

programme, we’ve transformed a 

traditional corporate office building 

into an innovative and futureproof 

workspace that’s at the cutting-edge of 

design. 

“With its potential to mitigate the 

impact of climate change while 

promoting health, wellbeing and 

biodiversity, Polypipe’s blue-green 

roof is a perfect example of the future 

workspaces of tomorrow, today. 

“The purpose of workspaces is evolving, 

and it just goes to show the integral 

role buildings such as Bloc will play 

in shaping communities and urban 

landscapes of the future.” 

Polypipe Civils & Green Urbanisation’s 

Permavoid solution has been used at 

Bloc to create the innovative bluegreen 

roof structure. The shallow subbase 

attenuation system, which is made 

from 100% recycled polymer, manages 

rainfall at source. 

This collected surface water is then 

either retained for re-use or gradually 

released to help prevent flooding ahead 

of periods of extreme weather. 


SOLAR PV 

REGULATIONS WILL DRIVE A 

MORE SUSTAINABLE MARKET 

With predictions of soaring demand for solar PV in new build 

housing, what are the prospects for the retrofit market? We 

asked Stuart Nicholson, Roof Systems Director at Marley and 

Stuart Elmes, CEO of Viridian Solar, for their views. 

With a 31% carbon reduction 

target, the proposed changes 

to Part L in 2022 could 

lead to a five-fold increase in the 

number of new homes built with solar 

technologies, according to Solar Energy 

UK. But how is the retrofit market being 

affected by the UK’s drive towards 

net zero carbon emissions? 

Market drivers 

Stuart Elmes, CEO 

of Viridian Solar 

(right), which is 

now part of Marley, 

explains: “The 

retrofit market for 

solar has historically 

been driven by the Feed-in 

Tariff scheme, which produced 

successive boom and bust cycles as 

consumers rushed to install solar PV 

before the next drop in subsidy. When 

the scheme finally ended in April 

2019, it caused the retrofit market to 

scale back to a model based on home 

improvement and reducing energy use 

and carbon emissions. 

“Now, in 2021, we are seeing a new 

set of market drivers, this time driven 

by government regulation rather 

than government hand-outs. This 

should create a more steady and 

sustainable retrofit market, without 

the highs and lows associated with 

some subsidy schemes. In England 

and Wales, there are already statutory 

minimum efficiency levels for private 

rented property and in Scotland, 

similar regulations are aimed at social 

housing. The required energy levels 

(EPC ratings) are readily achievable 

for all but the poorest performing 

properties. However, the intention is 

that these regulations will become 

tougher over time, to align with national 

environmental standards. 

“Solar PV is a very convenient way to 

meet regulations like these because 

it requires relatively low 

disruption to the property 

and residents. The industry 

is already seeing large 

contracts for retrofit solar 

PV on social housing in 

Scotland, as a result of 

the Energy Efficiency in 

Scottish Social Housing 

regulations (EESSH). 

“Indeed, social housing providers 

across the whole of the UK are 

increasingly referring to ‘No Regrets 

Refurbishment’, which means avoiding 

doing things and then having to come 

back and do more work to meet new 

energy efficiency targets. A classic 

example of this is roofing replacement. 

If a housing association is 

going to refurbish the 

roofs of properties and 

they need to engage 

tenants, appoint 

contractors 

and incur the 

expense of 

scaffolding, then 

why wouldn’t 

they install solar 

PV at the same 

time? We are seeing 

more and more social 


housing providers looking to combine 

low carbon retrofits into their asset 

management programmes.” 

Purchasing influencers 

When it comes to private 

homeowners and 

occupiers, Stuart 

Nicholson, from Marley 

(left), says that many of 

the factors influencing 

new build buyers to 

choose properties with 

solar panels, are the same 

for those looking to retrofit 

solar PV: “People have become 

much more conscious about reducing 

their own impacts on the environment, 

alongside the need to reduce high 

energy bills and this is a driver in the 

private retrofit market. However, an 

even more significant factor is going 

to be the Government’s ban on all 

new diesel and petrol cars from 2030. 

This will represent a huge increase in 

demand for electricity for charging 

vehicles at home over the coming 

years. Electricity is expensive, so onsite 

electricity generation will become 

increasingly appealing to home owners, 

as well as social housing providers. 

“In addition, the cost to install solar 

panels has reduced dramatically over 

the past ten years, making it much 

more affordable and the potential 

savings and return on investment are 

very good. Prices are now around 75% 

cheaper than they were back in 2010, 

and the cost of battery storage is also 

becoming much cheaper, due to the 

automotive sector creating volume 

demand for use in electric vehicles. 

“New integrated systems, like Marley 

SolarTile, also make retrofitting very 

easy because they simply replace 

a section of roof tiles and have an 

easy push together design. Whereas 

previously consumers may have been 

put off by bulky on-roof systems, 


Images show solar 

PV installations, all 

courtesy of Marley 

and Viridian Solar. 


SOLAR PV 


these discreet, integrated panels are 

incorporated into the roof surface, 

acting as an MCS 012 approved building 

material and becoming a seamless part 

of the roof design. This makes it easier 

to pass difficult planning conditions 

and they have even been approved for 

use on heritage sites and conservation 

projects.” 

Indeed, integrated systems are 

becoming more widely used on retrofit 

projects, particularly among local 

authorities and this is expected to 

follow suit in the private homes market, 

as the aesthetic, maintenance and 

installation benefits are realised. 

Stuart Nicholson adds: “As well as the 

aesthetic benefits, integrated systems 

offer some significant advantages, 

including much easier maintenance. 

Unlike on-roof systems, both tiles and 

PV are installed together, which means 

there is no modification to the roof tiles, 

securing the manufacturer warranty 

and reducing the risk of breakages or 

cracks. Our integrated solar panels also 

prevent the problem of bird infestation 

and provide excellent weathertightness, 

wind and fire resistance.” 

Contact Marley 

and Viridian Solar 

www.marley.co.uk/solar 

www.viridiansolar.co.uk 

Tweet: @MarleyLtd / 

@viridiansolar 


SOLAR PV INTERVIEW 

NAVIGATING THE 

‘SOLAR COASTER’ 

The solar PV sector of today is drastically different to that of 

ten years ago. Christelle Barnes (below), Country Manager 

UK at SolarEdge, discusses riding the ‘solar coaster’ and 

navigating the industry’s ever-changing landscape, but also 

explains why things are looking positive moving forward. 

The UK solar PV industry is no 

stranger to turbulence. The 

twists and turns of the wild ‘solar 

coaster’ ride, set in motion following 

the launch of the government’s Feed-in 

Tariff scheme back in 2010, have 

transformed the sector to something 

very different to what it was ten years 

ago. 

“Previously, there were a lot of 

companies that just did electrical 

work, and then they’d start adding a 

little bit of solar,” explained Christelle, 

who is well placed to comment on 

developments within the market. “Or 

they just did roofing and started adding 

a little bit of solar, and then they found 

that it wasn’t sustainable for them to 

continue. So now it’s more dedicated PV 

companies. 

“The PV industry of 2021 is very 

different to the PV industry of 2010, 

when it really took off in the UK. We 

have a lot more solar installed now, so 

there are more challenges on the grid. 

We have a more sophisticated buyer, so 

our installers need to be at the top of 

their game. 

“And we have a lot of different sectors 

that are using solar. Now we have the 

local authorities making decisions for 

housing association portfolios. We have 

the new-build market and housing 

developers having to tick boxes, and 

then we have private homeowners and 

the whole commercial sector as well. 

So, there’s a lot of different elements 

to it…” 

Founded in 2006 with a focus on 

module-level power electronics, global 

company SolarEdge set out to change 

the way solar power is harvested and 

managed in the PV system, and to 

address “shortcomings” with the PV 

technologies of the time. 

The traditional string inverter lacked 

what Christelle describes as “enhanced 

digitalisation or cleverness”, and was 

limited by a ‘domino effect’ 

which meant that the underperformance 

of a single 

solar panel would reduce 

the efficiency of all the 

other panels on the same 

string. 

Christelle explains: “With 

the traditional inverter, the 

whole system is connected 

together on one string. This 

basically means that if one panel is 

shaded, the performance of all the 

other panels on that string is impacted 

– so if a bird lands on one module for 

five minutes, the power from every 

module in that string drops down to the 

same level as the one with the bird on. 

“There are no electronics up on the 

roof so the inverter doesn’t know 

that there’s something wrong with 

one panel. It just sees a reduction of 

performance coming from the whole 

system.” 

Looking to address these issues, the 

SolarEdge system features a Power 

Optimizer which allows each panel to 

work individually at its maximum power 

point, ensuring that 

unlike traditional 

systems, if one 

‘domino’ falls, the rest 

of the system continues 

to operate at maximum 

capacity. It also gathers all of the 

information about system performance 

at a panel level, which can then be 

sent directly to the system owner or 

maintenance team via SolarEdge’s 

cloud-based monitoring platform. 

The SolarEdge product was launched 

in 2010 and “I think it’s fair to say that 

the response was quite positive,” says 

Christelle, “because we’re now the 

biggest inverter manufacturer in the 

world.” 

In what Christelle describes as a “very 

up and down kind of 12 months” for 

most in construction, SolarEdge has 

seen different sectors strengthening 


and weakening on a quarterly basis: 

“Through the first lockdown a year ago, 

the residential market really was very 

quiet, with everyone trying to figure out 

how to work in this pandemic, whereas 

the commercial market did continue,” 

she says. “There was obviously a little 

bit of confusion at one point about 

whether construction sites were 

allowed to remain open or not… then 

we found that the commercial market 

became more cautious.” 

Fast forward to 2021, and it’s the 

commercial sector, which includes 

large-scale public sector projects as well 

as businesses, that’s showing signs of 

strong growth, with the Public Sector 

Decarbonisation Scheme Funding 

expected to bring a ‘huge pipeline’ of 

projects to fruition. 

“I believe that in 2021, we’ll likely 

see the strength in the commercial 

market, in particular, through public 

sector projects,” says Christelle. 

“Residential is not doing badly, but 

it’s been challenging, I think, through 

this pandemic for a lot of companies. 

Looking ahead, our focus is providing 

solar installers with the tools to boost 

their businesses.” 

With the bulk of its UK business in the 

retrofit sector, SolarEdge maintains a 

strong commitment to training in the 

UK, reinforced by the requirement for 

companies here to be MCS approved. 

“I think especially in the UK,” says 

Christelle, “because of MCS there’s 

been a focus on training from the very 

beginning – and on having accredited 

installation companies. So, we’ve always 

been very committed to the UK market 

and making sure that our installers 

have all of the tools that they need 

to operate to the best of their ability. 

We’ve always had a training programme 

on offer and we’ve expanded that out, 

through the last 12 months, to include a 

big focus on the Edge Academy.” 

Described by Christelle as the “next 

step” for committed professional PV 

installers who already understand the 

basics of the PV, the Edge Academy 

caters for those seeking to “evolve in 

knowledge” and become a specialist in 

their chosen PV technology. 

“It’s a place where our installers can go 

to really excel… to make sure that they 

are offering the best solution for their 

customers because they have the full 

knowledge about the product range. 

“And when they’re installing a 

SolarEdge PV system, it’s with absolute 

confidence that they’re doing it in the 

most efficient way. So, it’s a course, 

that’s really focused on our products… 

it’s continually evolving and there’s lots 

of nice plans for the Edge Academy this 

year, with new courses being added.” 

Looking to the future, Christelle 

acknowledges the changing motivations 

of the consumer, pointing out how 

the financial incentive for consumers, 

initially driven by the government’s 

Feed-in Tariff, has given way to those 

who choose solar because they 

care about their carbon footprint, 

about tracking expenditure, reducing 

electricity consumption and doing so “in 

the most easy to use way.” 

“And that’s where solar has really risen 

in popularity, because it’s relatively 

easy for people to install. It’s a 

straightforward technology,” she says. 

“I think the persona of the buying 

profile has changed a lot over the last 

couple of years, which has probably 

been partly driven by the pandemic 

and the shift to working from home, 

as well as the big increase in electric 

vehicles, all of which need to be charged 

at home. Electricity consumption is 

Main pic: Rooftop solar 

install. Inset: Christelle 

Barnes, Country Manager 

UK at SolarEdge. 



SOLAR PV INTERVIEW 


increasing and people don’t like that. 

They don’t like having to pay more 

on their direct debit every month. So, 

they’re looking for ways to reduce that 

and they’re choosing technologies that 

are smarter… it’s a really interesting 

transition of the market and it applies to 

the commercial sector as well.” 

So what’s next for the solar PV 

sector? 

“We’re still learning about the Future 

Homes Standard and reading about 

what it means for us as a manufacturer 

and what our customers are going to be 

looking for from us in the coming years. 

But I think that the market and the 

industry are going to continue to evolve. 

I’m sure there’ll be new challenges that 

crop up along the way that we haven’t 

thought of yet… 

“I don’t know what’s going to happen 

in a year or two years, three years 

from now, but I know that our team 

will continue to introduce innovative 

solutions to any issues that arise.” 

While Christelle, doesn’t have a crystal 

Advancements in safety will be important 

for the sector moving forward. 

ball, she thinks there might be more 

focus on the invisible components of 

PV systems that affect things like safety 

standards. “The industry already ticks a 

lot of boxes when it comes to things like 

safety features,” she says, “but I think 

we’ll continue to set new benchmarks 

when it comes to technology 

advancements for higher levels of 

safety, offering further cost- and timeeffective 

benefits. … There’s a lot of 

focus also on those really important 

features that are absolutely critical to 

the success of the industry.” 

The last year has been tough for 

everyone but according to Christelle, 

there are plenty of reasons to be 

cheerful thanks to a strong commercial 

market. “We’re seeing our installers are 

super busy and reporting really strong 

pipelines,” she says, “and there’s a 

general positive feeling in the industry, 

so I think we are looking forward to a 

positive year ahead. 

“As an industry, we’ve got through 

Brexit and we’ve got through a 

pandemic. We’ve taken another loop of 

the ‘solar coaster’ and we’re still here.” 

Contact 

SolarEdge UK 

www.solaredge.com/uk 

Tweet: @SolarEdgePV

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