Retrofit & Replicate - Hyde Housing Association

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Despite all the carbon reduction measures described above, the scheme was still estimated to fall short of achieving the 80% target, largely because of its relatively good SAP rating at the outset. Bridging the shortfall would require the input of renewable electricity micro-generation, with photovoltaics considered the only viable solution. Working with Solar Technologies, proposals for an array of eight panels located on the rear extension roof were developed. Bearing in mind the short lead-in time, product availability and the need for grant funding, Solar Technologies recommended Sharp 170W polycrystalline panels, to be laid at a pitch of only 5° to limit any impact on the neighbouring property. A single inverter has been located in the existing ‘electrical’ cupboard and a wall-mounted display will inform the incoming tenants of its electrical contribution. The graph opposite shows the impact that each of the measures implemented at the property have on the associated CO 2 emissions. The insulation measures alone account for over a quarter of the original emissions, or a third if the triple glazing is included. The greater efficiency of the condensing boiler then takes the improvement to over 50%, after which the returns on investment are less dramatic. Nevertheless, the introduction of MVHR and airtight construction should contribute a further 15%, with the solar thermal and LED lighting taking our overall reduction to 76%! The photovoltaic contribution allows the refurbishment to easily achieve the target with a built-in contingency for actual performance in use. The high levels of energy conservation and generation are reflected in the provisional EPC rating of 92, placing the property in the highest Band A. Predicted specific primary energy use at the refurbished property is estimated at 67 kWh/ m 2 /yr with CO 2 emissions reduced to 17 kg/ m 2 /yr and space heating demand reduced to 32 kWh/m 2 /yr. Fuel poverty should never be a concern for one lucky tenant! Though driven primarily by low-carbon targets, the project offered an opportunity to incorporate other sustainable refurbishment measures. Water conservation measures are also a key interest for Hyde and the two bathrooms will subsequently be fitted with Twyford Galerie Flushwise (2.6l/4.0l dualflush) wc’s, aerated basin taps, Mira Eco shower handsets and a low volume bath. The project team did not consider conventional rainwater harvesting, stored underground and pumped up to a header tank, to be viable for a stand-alone property - primarily in terms of the installation and maintenance costs but also in terms of energy and carbon savings. A recent study by the Centre for Alternative Technology (CAT) has proven that the embodied energy consumed in the manufacture of buried tank systems is never paid back through its life by the savings made from utilising rainwater. However, ‘Retrofit and Replicate’ partners Parity Projects have experience of installing simple gravity-fed harvesting systems and have designed a proposal based around a filtered 318 litre tank located in the void above the stairs. The tank is fed directly from an external downpipe, requires no pumps and therefore requires no parasitic electricity and next to no maintenance. Parity Projects’ calculations indicate that virtually all of the water required for flushing could be supplied from the annual average rainfall locally. A meter on the backup supply will determine actual annual mains water consumption. - 5 -
Materials specifications generally reflects the environmentally-friendly aims of the project, for example: • FDT Rhepanol pvc-free single-ply roof membrane to the rear extension • Finnforest Thermowood fascia cladding boards • Lindab Rainline steel guttering These materials have been selected because their manufacture and processing avoids the use of toxic materials. Typically they are durable products that require minimal maintenance and can be easily recycled at the end of their life. Internally, the focus has been on responsible sourcing and avoidance of materials prone to off-gassing wherever possible. This is especially important in a dwelling where air leakage and draughts are very low. Timber used throughout the house is either softwood or occasionally temperate European hardwood, with FSC or PEFC accreditation. Natural products have been selected for floor finishes as far as possible, with Tarkett Marley Veneto XF linoleum flooring in the kitchen and an eco-wool carpet to bedrooms and hall areas supplied by the Alternative Flooring company. The latter has even been laid on a recycled rubber underlay! The access door to the rainwater harvesting cupboard was fabricated in MDF for ease but the zero-formaldehyde Medite Ecologique was used in lieu of conventional fibreboard. In the garden and driveway the tenant has been provided with the tools to help with a greener lifestyle, for example: • raised planter to encourage home-grown vegetables • twin composting bins • rainwater butt to store water for use in the garden • a rotary washing line • recycle box storage Internal decoration has been carried out throughout the entire house postrefurbishment – paints were generously supplied by Dulux Trade from their Ecosure and Light&Space ranges. Working with consultants from their in-house team, the specifications have been selected to highlight their performance credentials, whether that be low VOC levels in the bedroom environments, improved durability and lifespan in the hallways or increased light reflectance in the living areas. The Dulux team will then benefit from the tenant feedback on the performance of these paint finishes over the two year monitoring period. In addition to carrying out the comprehensive eco-refurbishment, Hyde will provide the incoming tenants with an understanding of how to best maximise energy savings and to optimise use of the property. We will then comprehensively monitor the property’s performance whilst in occupation, in order to give us a thorough understanding of what technologies best work in terms of CO 2 savings, energy efficiency and cost effectiveness. Working with Parity Projects, thermocouples are being installed across all wall and roof constructions. These temperature readings will be recorded and uploaded directly to a datalogger, together with ongoing electricity, gas and water usage. Furthermore, a heat meter linked to the output of the Vaillant ecoMAX condensing boiler will provide details of the actual energy used for space heating and supplementary hot water at the property. Uploading this information to a PC-based software package will allow continuous remote monitoring and analysis of the property’s energy use and emissions. In addition to the quantitative data PPCR will undertake post-occupancy interviews conducted throughout the monitoring period to assess resident reactions to the eco measures employed and their impact on comfort and satisfaction. The refurbishment can greatly reduce carbon dioxide emissions, but another crucial question is: ‘What’s it like to live in?’ PPCR will conduct a complimentary exercise with a family living in a nearby similar but non-refurbished property as a comparator. They will discuss general aspects through a questionnaire type agenda with each household member able to contribute, for example: · Does living here seem any different to another home of this type? · Does the ‘ecohome’ present any requirements for lifestyle changes? · Are there any aspects of the measures that are difficult to use/understand? · Are there any measures you would like to change? Why? · Do you think it would work for all tenants/families? · What are the benefits of living in an eco-home? Of equal importance to reductions in carbon emissions are the financial savings to residents resulting from the significant reduction in energy consumption. We estimate that energy consumption will be reduced by up to 85% with a saving to the residents of around £600 per year as a result of the retrofit we are carrying out (at current energy costs). This project can therefore make a major contribution to the growing problem of tackling fuel poverty. At the end of the project we will be able to produce cost benefit analysis for each of the eco measures adopted. This information will be disseminated publicly and will specifically inform Hyde’s future stock investment and refurbishment plans. - 6 -
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