Rather than investing in any form of power generation, it is more cost-effective for homeowners to first invest in what’s needed to reduce their building’s energy demand. This is a principle known as ‘fabric first’. However, this principle is often ignored when homeowners are looking to save energy. Research has shown that improving the energy performance of a building is likely to have greater cost savings over the long term than incorporating renewable systems.
Start with the building envelope
First, fix things first. Loft insulation, cavity wall treatment, and double glazing all reduce the rate at which your property loses heat on any given day. If you generate electricity on-site, but your building burns an optional amount of the stuff, you might as well try to fill a bucket using a sieve. For a typical building, bridge heat (sometimes referred to as thermal bridging) accounts for about 25% of this preventable loss. Heat escapes (or enters the building in the summer) through gaps and inadequately insulated structural elements like window frames and even wall ties.
Electrify the heat, then power it yourself
Dependence on gas for heating comes with a risk most of us simply live with: fossil fuel prices jump around. The price of gas has more than doubled in the last year, and it’s unexceptional for it to surge like that. Twice in the past 15 years, it rose quick and stayed high for half a decade. There’s nothing built-in to ASHPs like there is for gas that lets you disengage, tick on through the spikes, and hope for a lower price next year.
An air source heat pump doesn’t create heat by combustion. It takes low-grade heat from the air – even as low as -25C – and through the magic of thermodynamics turns that into thermal heat for your building. “Magic” in this instance means for every 1 unit of electricity you put in you get 3 or 4 units of heat out. That’s the only way electrified heating can compete with fossil fuels, particularly gas. It’s also how adding on-site generation can fundamentally change the financial case for renewables.
Provided you’ve got a property already running an ASHP, you’re not buying whatever the latest annual gas hike tells you to from the ‘big six’; you’re benefiting from the falling cost of lithium and IRRs on domestic solar by turning the heat on when the sun is shining. Solar panels generate direct current electricity from photovoltaic (PV) cells, giving your heat pump something to do – either warming your hot water or circulating through your wet UFH system to warm your floors. Around that, it’s the inverter’s job to convert that electricity into grid-tie AC to keep the rest of the lights on. Any additional electricity can be stored in a lithium battery ready to use in the evening, or exported back to the grid under the Smart Export Guarantee.
A typical home could save between £210 and £514 a year just on their electricity bills with a standard solar PV installation. Timing is everything when it comes to making the most of your solar energy system. The good news is that smart home energy management systems are getting better and better at it.
Calculate the real return, not just the bill savings
Every capital investment in a property should be seen as exactly that, an investment, not a cost. For home energy upgrades, this translates to the payback period – the point at which accrued savings and export revenue exceed the installation outlay.
A solar PV system with battery storage, fitted to a property already properly insulated and heated, will typically hit payback more quickly than one tacked onto an energy-gobbling building with no thermal upgrade. The devil’s in the detail: roof aspect, shading, system size, grid export tariff, how much of the electricity generated is used directly in the building.
Long-term financials aside, there’s the EPC rating. Properties with an ‘A’ or ‘B’ Energy Performance Certificate tend to sell for a premium compared to equivalents with lower ratings in the marketplace. Growing numbers of buyers are aware of total occupancy costs, and a proven high-efficiency property is a cheaper-to-run fact on legs.
The broader shift in how we think about property
A house that produces its electricity, saves the surplus, and has effective heating from clean energy sources is not only less expensive to maintain. It is protected from the energy market changes in a manner in which a gas-reliable property could never be. Microgeneration on a personal level is as much of a hedge as it is a mark of being environmentally conscious.
The beauty of making these changes is that they feed off each other. Better insulation leads to a lower amount of energy needed. Lower energy consumption means that your system can cover a higher percentage of your needs. A smaller system together with storage means less reliance on the grid. If done correctly, all of these steps form a solid financial plan, rather than just some sustainable purchases.
