Could an eco build be your wisest investment? 

After the uncertainties of obtaining planning permission, applying for Building Regulations approval can seem positively balmy. The regulations, after all, are concerned solely with objective facts and figures, rather than opinions or interpretations of policies. And they have your interests at heart, ensuring your new home, extension or renovation won’t fall down, leak, catch fire, explode, electrocute or otherwise harm you.

Over the years, however, their remit has steadily expanded from improved safety in glazing and electrical systems to provisions for disabled access. But the most significant measures have been to combat the effects of global warming. Today they require the highest ever levels of insulation and airtightness in new homes, double glazing and energy-efficient condensing gas boilers. 

But far more radical measures are due to be announced later this year, following the government’s 2019 decision to make the UK net zero carbon by 2050. They will form part of the Future Homes Standard, also announced in 2019 and due to come into effect in England and Wales in 2025. 

All new homes and extensions will need to reduce their carbon emissions by between 75 and 80 per cent of those built today. That will effectively mean no more connections to the gas network.

Full details haven’t been announced yet, but all new homes and extensions will need to reduce their carbon emissions by between 75 and 80 per cent of those built today. That will effectively mean no more connections to the gas network. Instead, domestic heating and hot water must come from low-carbon sources. Air or ground source heat pumps are the government’s current favourite. 

How likely is all this to happen? Well, UK governments have been rather better at making climate change pledges than actually enacting them. Remember the 2006 Code for Sustainable Homes, promising all new homes would be zero carbon by 2016? Or the 2013 Green Deal for energy-saving home improvements? Or the Green Homes Grant, doing much the same, launched last September and abandoned six months later?

Of course, until the latest changes come into force, the current regulations apply and, once granted, remain legal for three years. But is it wise to proceed on that basis now? Ron Beattie, MD of eco builders Beattie Passive, believes not. The proposed upgrades, he argues, should be done now. ‘If we don’t do it now,’ he warns, ‘it will cost us two or three times the current price.’

So what exactly should we do? One solution is to adopt the Passivhaus system. Developed in Germany, it’s a method of guaranteeing the performance of a new building, something current Building Regulations don’t manage very well. 

Passivhaus succeeds by combining very high levels of insulation with an airtight building envelope, alongside computer modelled specifications and rigorous testing throughout the build. As a result most of the heating comes from ‘passive’ sources: solar warmth, the heat of appliances and the occupants’ bodies.

MVHR

To distribute it evenly and keep the atmosphere fresh, a whole house mechanical ventilation system is used. Warm, moist air is drawn continuously from kitchens, bathrooms and utility rooms and replaced by fresh air distributed to living areas. A fan, usually sited in the attic, does the work, often combined with a heat exchanger, extracting heat from exiting air to pre-warm incoming fresh air. The result is an even temperature throughout the house, very low fuel bills and high levels of comfort.

Image: MHVR system from Zehnder.

But how much does it add to standard building costs? Between 10 and 25 per cent is a common estimate, though that doesn’t take account of ongoing fuel savings.   

There are, however, more immediate financial reasons for eco building. Until fairly recently the Ecology Building Society was the only UK mortgage provider offering green incentives to borrowers. Their C-Change discount includes 1.25 per cent off their standard mortgage rate for a Passivhaus self build and 0.75 per cent off for a new build or retrofit boasting an Energy Performance Certificate rating of ‘A’ or above. 

Today, however, over two dozen lenders offer either discounts or cashback for properties with similar EPC ratings. Nationwide is offering existing mortgage holders a discounted rate on extra borrowing of up to £25,000 if at least 50 per cent is used for energy efficiency home improvements. They include air or ground source heat pumps, electric car charging points and even small-scale wind turbines. 

The single major decarbonising expense, however, remains heat pumps, which cost from £8,000 upward. Not quite the £2,500 or so of current gas condensing boilers. 

But the government’s Domestic Renewable Heat Incentive, launched in 2014, still offers seven years’ worth of tariffs to subsidise renewable technologies. These include heat pumps and solar thermal panels. Applications remain open until March 31, 2022. Details are on the Ofgem website.

What is predictable, however, is that a highly insulated, airtight home with a good ventilation system will use the least amount of energy, regardless of its source.

But by 2025, who knows? The gas heating industry seems to be pinning its hopes on hybrid systems: heat pumps as the main source of heating, but with gas boiler back-ups – perhaps using biofuels or even hydrogen, though currently it remains prohibitively expensive. Or could district heating transform the efficiency and cost of domestic heating? 

What is predictable, however, is that a highly insulated, airtight home with a good ventilation system will use the least amount of energy, regardless of its source.

August 2021