Who needs retrofit standards?
We all do, argues Dr Peter Rickaby, but the goal of mass retrofitting our energy inefficient building stock is hampered by the fact that when it comes to most retrofits, we simply don’t know what we’re trying to achieve.
This article was originally published in issue 18 of Passive House Plus magazine. Want immediate access to all back issues and exclusive extra content? Click here to subscribe for as little as €10, or click here to receive the next issue free of charge
If we in the UK and Ireland are to meet our national emissions reduction commitments we must improve at least twenty million UK homes and one million Irish homes by 2050, and we have to do it properly, but very few of us engaged in retrofit (except those delivering Enerphit, the passive house retrofit standard) seem to know what we are trying to achieve. Are we aiming to reduce fuel costs, reduce fuel use, reduce emissions, alleviate fuel poverty, eliminate condensation and mould, or all of these? And by how much? Is it 80%, or 60%, whatever is funded, whatever we can manage or whatever is not too challenging? I have seen projects adopt all of these approaches. Our national objectives need translating into retrofit standards, because if we leave people to decide for themselves what standard to work to, the outcome is unlikely to be good enough.
We should begin by addressing fuel poverty. People who cannot afford to keep warm and have mouldy homes are not interested in reducing emissions, so eliminating fuel poverty comes first. There is little point improving homes to deliver affordable warmth now, because we know that fuel prices will rise after 2020, so with a view to 2030 we should be improving homes to at least the top of energy performance certificate (EPC) band C, a SAP energy rating of 80. The UK fuel poverty regulations encourage landlords to improve homes out of EPC bands F and G, but unless those homes are improved to SAP 80, the investment will be worthless in a few years as fuel prices rise.
There are some energy standards for retrofit. The building regulations include elemental standards (maximum U-values for building elements and minimum efficiencies for services) but there is no whole-building standard. Enerphit provides a comprehensive, detailed, whole-house standard that comes close to 80% emissions reduction, but even passive house enthusiasts acknowledge that Enerphit can be too challenging. Good practice is probably somewhere in between, but the STBA (Sustainable Traditional Buildings Alliance) and others tell us that deep retrofit of older, traditionally constructed buildings is not prudent. A Bristolian’s Guide to Solid Wall Insulation suggests that internal solid wall insulation should not exceed 60mm thick, achieving a U-value of just 0.6 W/m2K.
The most persuasive argument I have heard about emissions reduction is that if we wish to reduce emissions by 80% we should retrofit every building to the best standard we can achieve, to compensate for the many buildings for which the best we can do won’t come close to 80%. However, we learned from Innovate UK’s Retrofit for the Future programme that reducing emissions by 80% costs approximately £90,000 per dwelling, one-off, or perhaps an average of £50,000 at scale. Because of the law of diminishing returns reducing emissions by 60% costs half as much: £25,000 per dwelling at scale. Reducing average domestic emissions by 60% will probably be enough if we can de-carbonise the electricity supply system sufficiently to deliver the other 20%.This seems plausible, and ignoring the supplyside contribution would be foolish. So 60% emissions reduction looks like a good standard to work to, provided we accept that it is an average. Eighty per cent or more is better, where possible.
Much recent retrofit has not delivered the expected savings, and has been of such poor quality that damage has been done to buildings and occupants’ health has been put at risk. Often these problems have resulted from poor assessment, poor design (or no design), failure to consider the interactions between measures, poor installation, lack of proper commissioning and inadequate hand-over. We need whole-building retrofit standards that protect the health and welfare of occupants and the integrity of the buildings by dealing with the end-to-end retrofit process in detail.
The Irish domestic retrofit standard, NSAI SR54:2014, provides a good starting point – it is comprehensive, technically sound and readily accessible as a free download to anyone in the industry.
The current UK standard for retrofit, PAS 2030:2014, was originally developed to support the Green Deal and the Energy Company Obligation (ECO), and was driven by ministers’ justifiable paranoia about ‘cowboy builders’. Consequently, PAS 2030 has little technical content, its focus is on installer competence. PAS 2030 is now being revised to support the next round of ECO. Design requirements are being introduced, and there will be material on the interactions between measures – both physical junctions and functional interfaces such as between insulation, ventilation and heating.
However, we still need robust, comprehensive and appropriate technical standards for retrofit. The quality criterion should not be whether the installer has been certified competent but whether the whole of the work carried out, from inception to handover, complies with such standards.This is the vision of BSIs’ Retrofit Standards Task Group, working alongside the implementation of the ‘Each Home Counts’ (Bonfield) review to develop a framework of new and existing standards to support a national retrofit programme. It’s a big task.