No, it’s not air conditioned!

OK, it does look a bit like an air con unit...

One of the first things people say when they enter the new loft is “Ooh, it’s got air con!” Wrong, but it’s an understandable mistake, because our air source heat pump uses the same technology in reverse to warm the room.

Want to know more about this incredibly energy-efficient way to heat your home? Click on read more...

There is a tiny radiator in the corner of the new loft room, but we doubt we'll need to use it. The space is heated in an eco-friendly way using the new Worcester Bosch Air to Air Heat Pump (from around £1,500 including installation). This hangs on the wall, with pipes connecting it to a unit outside, just like an air conditioning unit.

We were befuddled by installation. This is no DIY job. It involves laying special pipes, charging them with refrigerant, vacuum pumping them to remove air locks and more. No wonder our builder was scratching his head after he read the instructions! Thankfully help came along in the form of Esas Ali, a specialist who covers the south east, whose team made light work of the installation.

The pump works like air con in reverse. It gathers heat energy from the air outside (even if that air’s cold, it still contains plenty of energy), carries it inside via refrigerant and then circulates it as warm air. The unit has a Coefficient of Performance of 4.5, which means that for every unit of electricity it uses to do the pumping it generates 4.5 units of heating power. That’s very efficient indeed, compared with an old-fashioned heating system.

It's perfect for the loft because the new room is sealed and well insulated. Shut the door on a cold day, turn on the pump and within minutes the room is nice and toasty without the expense of heating the rest of the house. It’s ideal for a home office because we used to waste a lot of money and energy heating the whole house with central heating on workdays, even though we were only using one room. The energy savings will be huge.