What to install, what’s simply not worth it and how you can optimise your installation for the best cost savings and result

By Simon Bones, founder & CEO of Genous

When talking about ‘renewables’ in a development, we can think about generation and storage technologies, which look to create a lower net demand for electricity (and since most people don’t have non-electric sources of renewable generation capability, we’ll restrict ourselves to this here), and equipment that seeks to replace fossil-fuel consumption with power generated from renewable sources – which tends to be about heating or transport. In each case, there are some technologies that, from my perspective, I like and others that I  think are oversold or just plain bad.

The good

Solar photovoltaics are a no brainer for housebuilders – and not just because the Future Homes Standard is going to mandate them. At current electricity buy and export prices, they give homeowners a real bill benefit, they are very EPC-friendly and there is never a cheaper time to put them in than when a roof is going in: in roof panels save on roof tiles, the scaffolding is there, and the wiring is easier when the building is still being put together. There is just no excuse for not doing this.

Home batteries. It’s easy to oversize, so this is about giving the resident future optionality. Batteries increase the benefit of solar photovoltaics by increasing self-usage, but they also allow moves to time-of-use electricity tariffs, making other home-electrification technologies work better. Clever specification can also reduce peak in-out electricity flows at a developmental level, potentially reducing enabling electricity infrastructure costs. Specifying hybrid inverters and modular battery systems so they can be easily added to is normally going to be the right approach here

Air-source heat pumps. Again, the default likely in an FHS world, air-source heat pumps are a proven technology, and can be used as either air-to-air (with warm air systems) or air-to-water) using traditional underfloor heating or radiators. The key is to integrate with battery storage (for time-of-use tariff optimisation) and to oversize radiators to allow a low flow temperature.

Shared ground loop heat pumps. Not really widespread yet, but the idea of doing ground-source heat pumps but using a shared ground loop for multiple properties is being touted as the next big thing. Allowing different properties to have their own controls but utilising a common infrastructure, the key challenge is around the cost compared to simple air-source units, but planning and noise challenges for dense building can render this a better solution in these situations.

EV chargers. Buyers increasingly expect EV chargers where off-street parking is available, and the units are inexpensive and can be throttled back when electricity demand is too high.

The bad.

Wind turbines. Aside from the planning and aesthetic challenges (and structural risks if not free-standing), wind turbines don’t tend to work well unless the area is extremely windy and/or the turbine is very big. Solar is a better option in our view at a residential scale.

Electric non-heat pump heating solutions. Heat pumps run super-efficiently, extracting heat from the air or ground or sources of water. Standard electrical heating either relies entirely on time-of-use tariffs (uncertain, structurally higher emissions) or provide less heat (e.g. radiant heating), and that has lower acceptance by some future residents. Heat pumps are normally just the right option.

The ugly.

Biomass boilers. There are restrictions in siting them, they produce smoke and require regular deliveries, the fuel is no longer as cheap as it was and while it’s circular it’s not always renewable – other options have got better, and biomass has been left behind. Reliability is also a concern; I’ve never met someone with a biomass boiler (including myself) who is entirely happy with it. 

Solar thermal made some sense (maybe) when solar photovoltaics were expensive and inefficient and subsidy/export regimes were different, but that’s no longer the case. Payback is slow, versatility is lower than for photovoltaics (you can only produce hot water whereas electricity can be used for lots of purposes, including hot water) and installation is more complex. There’s no need for this technology in our view.

So there you have it: home electrification, using photovoltaics, home batteries, heat pumps and EV chargers is the best renewables combination for modern homes – compatible with FHS, good economically for the future user of the property and, if well designed, the systems can be designed to reduce the additional electrical reinforcements that will inevitably be required.