STEP 2 Insulation

“The cheapest energy is the energy you don’t use,” says Joanna O’Loan, knowledge manager for the Energy Saving Trust. “So, yes, the more insulation that you can put in, the better.” While we all know that laying insulation in the loft is a smart move (and can be completed at cost by a confident DIYer), there’s a more complex world of insulation out there – especially if you would like your brand new heat pump to work at capacity. “Everyone should do their loft and cavity walls, if they have them,” says O’Loan.

However, most walls that were built before 1920 will be solid, and if you are one of millions living in a Victorian semi or terrace, you are potentially losing 35-40 per cent of your heat through the walls. “Solid wall and floor insulation is expensive and, being realistic, a lot of people won’t be able to afford it,” says O’Loan. “Also, it can make your rooms smaller – it may add around six inches to the width of the wall.”

But crucially, if you can’t insulate your walls it doesn’t mean you can’t have a heat pump. “We often pair pumps with underfloor heating, as you’ve essentially turned your floor into a radiator – so you can run at a lower temperature as you’ve got more surface area,” says O’Loan. “But if you’ve already laid an expensive floor, I’d suggest larger radiators – maybe 10 to 20 per cent bigger.”

If you can insulate, however, you absolutely should. “Some people are going straight for heat pumps, and that will work; they’re designed to work in any building,” says Smith. “It’s just that when you’ve properly insulated, you’ll probably need a smaller heat pump, and it will be more effective and require less maintenance.”

Aside from walls, ceilings and floors, windows and doors also need to have a high energy rating (A-A++) and should be well sealed to exclude draughts. Ventilation, however, should not be forgotten because as we seal up our homes, condensation can occur. “I recommend having trickle vents in windows,” says Smith.