Updated – 13th June 2022
Summary: Fabric first deep retrofit, aimed at make an energy intensive bungalow into a cosy low maintenance home with efficient use of renewable technologies.
We bought the bungalow in 2021 with the intention of making it our long term home.
- To make the dwelling more efficient and as environmentally friendly as possible.
- To make the living space all year and times useable, with our lifestyle in mind.
- Addition of greener travel facilitation.
Condition Before Modifications
As purchased the bungalow did not make best use of its position, the conservatory tended to be too hot in summer and too cold in winter, and the sunny side garden was under utilised.
It was not well insulated, which meant that while warm the gas boiler worked hard.
Taking a fabric first approach, heat loss from the house was addressed in multiple ways:
- Increased insulation in the attic space: as the attic is used for storage a raised floor was installed below which the insulation was placed, so that full thermal insulation was achieved.
- External insulation was placed on the outside of the house: keeping the walls inside the insulated space provides thermal storage in the walls, that helps keep the house warmer in winter and cooler in summer.
- Triple glazed windows and new door: provide better insulation and are positioned relative to the external wall insulation to avoid any thermal bridges which would otherwise loose heat from the existing walls.
- The conservatory was replaced with a fully insulated space.
Integrated system of renewable energy technologies have been installed:
- Air source heat pump (ASHP): Mitsubishi Ecodan 11kW (output) provides heating and hot water, operates with a CoP (coefficient of performance) of 2.7, as 1kW of electricity produces 2.7kW of heat – not silent 60dB.
- Thermal store: the ASHP heats a 250l tank this allows the heat pump to operate at optimum efficiency – not exactly small, lots more pipes and ancillary than a condensing gas boiler.
- Solar panels: 15 panels providing up to 4kW of electricity are installed on 2 sides of the house to take advantage of the sun through a large part of the day. Each panel is separately controlled so if some panels are in shade the other panels will still operate at full output and not be limited by the other panels.
- Batteries: 3 x 3.3kWh batteries allow renewable energy to be used even when the sun isn’t shining.
- Electric vehicle charging: the 2 EV charging points are able to adjust the rate of charging to use excess solar power when the sun shines.
Outside the bungalow is now rendered with solar panels rather than brick.
Inside the major difference is the uniform temperature throughout the house.
On a cold day you will hear the air source heat pump operating around the back
Things to Note
The project has been a learning experience and not been without its hiccups.
Air Source Heat Pump
- Heat pump uses a lot of energy (11kW heat / 3kW electricity) so costly in winter months.
- Heat pump is very noisy 60db.
- Internal pumps are noisy and need setting to be off at night or run constantly!!
- Lots of water produced as condensation ,needs drain
- RHI issues ,you must be fully insulated
- Be prepared for your EPC to get worse if you have moved from Gas
- Very large tank , have you the space
- No fits payments
- What tariff do I use?
- Upfront cost
External Wall Insulation
- Love it or hate the changed aesthetics
- Can’t get anyone to do it!
- Purchase cost (especially if you buy a Tesla :-))
- Range and Charge infrastructure worries (range anxiety particularly if you don’t buy a Tesla, as Tesla has an exclusive extensive charging network)
- New technology so unknown reliability and costs to repair once warranty ended
- Speeding tickets (especially if you buy a Tesla)