The housebuilding sector will see considerable change if, as intended by the previous government, changes are made to replace the Standard Assessment Procedure (SAP) with the Future Homes Standard (FHS).
With every indication that the government intends to roll out this change, it is interesting to consider its wide-ranging impact. I can volunteer a broad perspective as I both design homes as a profession and have also undertaken what might be described as an experiment, to adapt my 1970s house to meet the energy efficiency ratings demanded by the Future Homes Standard.
Understanding the challenge
As an initiative to increase energy efficiency, the FHS is very welcome. However, concerns have been raised, particularly regarding the Home Energy Model (HEM), a computer program to assess a building’s energy efficiency in place of the SAP.
The pros and cons of change
The proposed changes aim to improve the accuracy and relevance of energy assessments. A more robust method could drive innovation in design and technology, creating greater energy efficiency. It could also create a level playing field for developers.
However, there are potential drawbacks. Developing and implementing a new method is complex and time-consuming which could lead to uncertainty as developers and building control bodies adapt to new requirements. At the heart of the issue, concerned have been raised, not least by the HBF, about the HEM’s accuracy and reliability. If the model overestimates energy consumption, it could lead to unnecessary costs and delays for developers, ultimately impacting the price of new homes; if it underestimates consumption the environment benefits would be lower.
Finding the right balance
It is essential to find a balance between environmental ambitions and practical considerations. Overly stringent regulations could stifle innovation and increase the cost of housing, hindering the delivery of affordable housing.
It is crucial that the government works closely with the industry to develop a realistic and achievable FHS. This includes ensuring that the assessment methodology is accurate, reliable and cost-effective.
As an architectural technologist, I believe we have a vital role in shaping the future of housing, by embracing new technologies and design principles to ensure that new homes are not only carbon neutral but also affordable and desirable. The success of the FHS depends on a shared commitment to building better homes. By addressing the concerns of the industry, the government has the opportunity to create a legacy of energy-efficient and sustainable housing for generations to come.
Home project
My personal experience highlights the potential for older homes to meet these standards.
I began my ‘experiment’ in the fortunate position of qualifying for a £10,000 Green Homes Grant because my wife and I are both deaf. This enabled us to purchase and fit an air source heat pump (which, at £10,000 is £7,000 more expensive than a conventional gas boiler). Air source heat pumps perform optimally with higher levels of insulation, which adds to the costs. In our case, it involved raising the floor to create underfloor insulation over 200mm deep, combined with additional internal and external insulation to complement our existing 150mm cavity wall insulation – approximately sixty sheets of insulation, which was a further cost. We also added 12 solar panels (at a cost of £13,000) on each side of the house (24 in total) and a 10kw battery. Unfortunately the cost to disconnect from the gas network is expensive, at £1,500-£2,000, and if this service isn’t paid for, the electricity company will make a standing charge.
Using the 1am-4am reduced tariff, we can top up our battery overnight as necessary, though the solar panels made a net gain of £100 last year so this is unlikely to be necessary.
Is it worth retrofitting a home?
Many people ask whether the extensive disruption and costs were worthwhile. The energy efficiency benefits are indisputable: our electricity and gas costs, previously £2,000-£2,400, were just £300 for the first year – but of course it will take many years to recoup the initial costs.
Another way of looking at it is that in 2024 our solar panels generated 3,049.8 kWh of electricity, equating to a saving of £750.86. We saved approximately £1,140 last year and our solar usage has helped reduce our carbon footprint by approximately 930 kg of CO₂ annually.
Any financial savings are only part of the objective and I’m personally very pleased to have completed the project because of the energy and emissions saved. But to appeal to those who don’t have the upfront funds or the benefit of a grant, retrofit won’t be viable until the costs are substantially reduced.
Benefits of HEM
Would my project have benefited from HEM? Yes and no. The property has now exceeded the FHS. Had HEM been in place a more accurate calculation which may have led to me to do less and save money. So the question of benefit depends on the objectives of the project.
The intention of the FHS is that new homes built from 2025 produce 75-80% less carbon emissions than today’s homes. My experience tells me that if a 50-year old home can bring about this benefit, the goal is realistic, in theory.
Economies of scale
For new homes, economies of scale mean that energy-saving features can be significantly cheaper. The inclusion of an air source heat pump and solar panels (taking into account the efficiencies of buying in bulk) in a new home may add between £7,000-£10,000 – but at a saving of £1,300 per annum, this quicky becomes a benefit.
Food for thought
Taking a step back and considering the bigger picture, I am concerned that we may struggle to find the 300,000 heat pumps (and installation expertise) needed, assuming that the government’s housebuilding targets are met. To put this in context, the UK registered 189,836 solar panel installations and 39,268 heat pumps in 2023, the latter representing a 19% increase on the previous year, according to MCS Foundation data.
And unfortunately, because solar panels and heat pumps aren’t typically enough to power a home throughout the day/year, energy must still be sourced from the Grid. To power homes using clean energy will requires a considerable increase in wind, solar and other sources of energy generation.
The industry certainly requires a more robust and accurate methodology as SAP calculations are based on information from 2010 (only SAP 10.2 has been updated more recently) and currently this creates difficulties in demonstrating compliance with the FHS.
I support the implementation of a sophisticated HEM which can help optimise the design of residential buildings for energy efficiency. By simulating the energy performance of different options, architects can identify the most effective strategies while maintaining comfort and functionality.
Alan Wright is a senior architectural technologist at Boyer (part of LRG).
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