Winter 2023

BIOSOLAR ROOFS
WHAT ARE THE REAL BENEFITS
OF A BIOSOLAR ROOF?
Luke Rootham AIoR, Technical Sales Manager, Axter and Michael Anaxagorou, Sales Director,
Axter, and member of the board of the Green Roof Organisation, discuss the whys, hows and
overall benefits of installing a biosolar roof...
With sustainability and
improving energy
performance top of mind
for many building owners, a biosolar
roof is a practical solution that delivers
on both fronts. Green roofs support
compliance obligations in areas such as
sustainable drainage and biodiversity
net gain. Combining these benefits
with a solar photovoltaic (PV) system,
not only offers energy generation and
lower bills, but research also shows[1]
that the two together achieve better
overall performance.
Why a biosolar roof makes your PV
panels work better
Solar panels naturally heat up as
they absorb and process sunlight.
As they rise above about
25 degrees Celsius, their
efficiency decreases quickly.
A green roof will cool the
ambient temperature, bringing
the efficiency of the panels
back up. This is because water
will evaporate from the vegetation
and the damp earth in a process
known as evapotranspiration,
negating the urban heat island
effect.
A biosolar roof with arrays
packed in too closely together
won’t result in all of the
benefits discussed, which is why
GRO (the Green Roof Organisation)
recommends[2] that where PV is
mounted on a roof, the application and
area of the green roof be maximised,
and panels should be spaced a
minimum of 750mm apart.
Article authors Luke Rootham (left) and Michael Anaxagorou (below).
Above: The Clapham Place biosolar roof project.
Why the solar panels
help the natural habitat
on your roof
The PV element of a biosolar
system creates a diversity in
the conditions across the
roof. Some portions will
be exposed, and others
shaded. Water runoff
from the panels will
collect, creating a mix of
damper and drier areas.
This creates what is called a
habitat mosaic, in which a wider
variety of flora can flourish.
The physical presence of the panels
also creates wind-shielded areas in
which many species will thrive. The
overall result is an increase and a
greater diversity in vegetation, which
will attract other life, such as butterflies
and birds, increasing the overall
biodiversity as a result of the biosolar
combination.
Case study: Clapham Place
Clapham Place is a major new
development in South London,
comprising 62 luxury flats, each with
a private balcony or terrace and
various other amenities. The project
was completed by Regal London in
2021, with Axter supplying the roofing
solution, combining Wilotekt Plus hot
melt waterproofing and a biodiverse
living roof finish, installed by chosen
partner TM Roofing. It is fantastic to
see nature thriving in the heart of the
metropolis as a result of this project.
Continued on page 22 >>>
20 GREENSCAPE WINTER 2023 • www.greenscapemag.co.uk