Garden flats needing refurbishment.
50-100 square metres.
Refurbishment is a great opportunity to replace an old or existing gas boiler with an electric alternative. A garden may have additional flexibility allowing the installation of heat pumps. Depending on the condition of the heating system and your budget, you have three options:
Install a heat battery boiler, like the Tepeo ZEB, to supply hot water and heating. You remove the existing boiler and plug in this new one.
90 to 140 square metre flats should be just within the ZEB's energy capacity. If your property is not well insulated you should look at Option 2 below.
Approximate cost: £6000 installed
Same as above, but combined with a smart water cylinder . The addition of the cylinder gives you more power output, more flexibility of use and ultimately reduces your bills because you are almost guaranteed to charge only at night. ((total cost of the transition: approximately £9000-15000, including VAT). You must check your incoming electricity fuse, as you will likely need at least 100Amps.
What else can you do?
The power required to heat the house ultimately depends on how well-insulated the building is and how efficient the heating system. It makes sense to address the building fabric and the heat engine simultaneously: improving the fabric reduces energy requirements and the cheapest energy is the one you don’t use.
Fabric first:Old buildings (pre-war) will not have cavity walls. Insulating walls from the inside can be tricky and expensive. Our advice is to advocate fabric improvements at the scale of the building to improve walls from the outside (where possible) and the roof. Instead, you can replace the windows and doors and improve air tightness by checking and insulating all the penetrations (pipes and ducts going out).