Deep retrofit standards
As shown in the previous section, much of the retrofit measures that have been incentivised through government have been via supplier obligations and market based policy measures. It can be argued that ECO and its predecessors have largely resulted in piecemeal implementation of the lowest cost measures in an unsystematic fashion. Further the Green Deal has had an extremely limited uptake and alongside the exclusion of technologies with positive marginal abatement costs, shown in It may also exclude those measures at the margins of the ‘golden rule’ given the high transaction costs associated with domestic energy efficiency.
Many in the industry feel that in order to realise the mitigation and fuel poverty reduction potential, a more comprehensive ‘whole house’ approach to building retrofit is needed. A non-exhaustive list of energy interventions for domestic properties is shown in. A number of pilot schemes have been implemented to explore the technical challenges and economic implications of comprehensive deep whole house retrofits. These are summarised in the following section
Figure Measures that may be undertaken during retrofit of a property
Retrofit for the future
Retrofit for the future was one such pilot project, whereby £17m of funding was allocated through the now disbanded QUANGO the Technology Strategy Board. The project involved 86 prototype homes with targets for an 80% reduction in CO₂ from an average 1990 baseline. For a typical 80m² semi-detached house with emissions of 97 kg CO₂/m².yr, this equates to a reduction to 17 kg CO₂/m².
The measures implemented were, also comprehensive in the sense that they were designed to address the whole dwelling following six themes;
Indoor air quality
Working on site
The measures typically included insulation to the entire building fabric, replacement of windows, increased airtightness, heat recovery ventilation, improved or renewable heating plant, smarter controls along with many instances of micro generation via PV arrays or solar hot water. On completion, 24 properties achieved carbon emissions less than half of the national average. 10 houses delivered 70-80% below national average with 11 properties achieving 50-70%. However only 3 of the 86 dwellings achieving an 80% reduction in CO2 emissions when compared to the national average, perhaps reflecting the difficulty in meeting the 80% reduction target
Superhomes by contrast, is a network of self-funded retrofit projects that have been undertaken to deliver 60%+ reductions in CO2 emissions from existing buildings. The National Energy Foundation (NEF) has provided professional support for SuperHomes since the Sustainable Energy Academy (SEA) initiated the project in2007/8. Superhomes has been constructed as a knowledge sharing platform with online forums, where users can share their experiences of undertaking deep retrofit projects. The Superhomes initiative also organises a number of open door events; whereby members are encouraged to share their experiences first hand with interested members of the public. With over 70,000 visits undertaken, around 190+ projects have been undertaken to the Superhomes standard to date.
This benchmarking issue is further complicated when considering that other retrofit standards adopt a requirement for maximum energy use. The demanding Enerphit standard is derived from the Passivhaus approach, whereby the focus is on meeting a maximum 25kwh/m2/yr. for space heating and also maximum 120kWh/m2/yr. primary energy consumption. The Enerphit standard is now being promoted internationally. These standards account for un-regulated energy use and do not factor in the use of PV cells as part of the primary energy target In this way it can be seen how the standard places a focus on mitigating the environmental impact of maintaining a comfortable internal temperature, as well as limiting energy intensive consumption. Unlike SAP; undertaking a PHPP assessment for a Passivhaus or Enerphit project typically takes a matter of days not hours.
BREEAM Domestic Refurbishment (BDR)
BREEAM Domestic Refurbishment is a performance based assessment method and certification scheme for domestic buildings undergoing refurbishment. This performance is quantified by a number of individual measures and associated criteria stretching across a range of environmental issues as described below, which is ultimately expressed as a single certified BREEAM rating, from Pass to Outstanding. BDR includes the following categories:
Health and Wellbeing
BDR is now being mandated by a number of local authorities, notably those in London, as a means of delivering sustainable retrofit.