Energy efficient council housing
All new council homes are being built with energy efficiency as one of the main priorities.
The homes are designed as mini power stations and are known as Homes as Power Stations (HAPS). They can generate around 60% - 80% of the energy you will consume and help to reduce your energy bills.
They have been built to a performance standard known as a Swansea Standard home, meaning that it is very well insulated and the energy required to heat it will be very low compared to a traditional home.
The homes are based around a thermally efficient and airtight structure designed to reduce heat loss to a fraction of that from a typical home. Energy is generated by using a Solar Photovoltaics (Solar PV) on the roof for electricity.
The energy that the solar PV generates is either used directly to power appliances and heating or is stored for later use in a Tesla powerwall battery housed in the property. The lithium ion battery stores energy generated during the day and releases it when required.
The central heating system uses a ground source heat pump which takes heat from the ground to heat the home and hot water. The hot water cylinder is part of the heating system and uses the heat from the ground and electricity to heat the radiators and water.
A HAPS home combines high level comfort with very low energy consumption. Components like double glazed windows, high levels of insulation and a Mechanical Ventilated Heat Recovery (MVHR) which provides you with good quality air and helps to reduce condensation and unpleasant smells.
How the heating differs from other houses
Most ordinary houses heat up and cool down very quickly, wasting a lot of the energy used to heat them in the first place.
That's why they often have heating systems that come on in the morning, go off during the day and then come on again in the evening. A HAPS home has a slower response and doesn't need that type of control.
In a HAPS home there is non-traditional heating and radiators but there is also:
Lots of insulation
The external walls are very thick; this is because they contain a lot of insulation. The floors and roof are also insulated, although this is harder to see. The windows and doors are also highly insulated, with double glazing. We make sure all these insulations join up so that there is no energy wasting gaps.
The house is designed to minimise draughts and provide you with fresh air all the time through a ventilation system. Vents in the ceilings supply fresh air into the sitting room/dining area and bedroom. These vents also extract the stale air from the kitchen, bathroom and WC. This system uses filters to ensure the air is always clean.
Not wasting any heat
The ventilation system cleverly recovers the heat from stale air and uses it to warm up the fresh air. The home is designed to capture the heat from the sun, from the appliances and even from the people living there. That way they don't need to pay for expensive energy to keep the house warm. Instead it keeps the temperature constant which means that the home will be comfortable all the time but will use a lot less energy.
A HAPS home has been built in such a way that it will require very little energy to keep it warm.
The house has a mechanical ventilation heat recovery (MVHR) system which uses a highly efficient heat recovering system to ensure that very little of the heat is lost from the out-going air. There are extraction vents in both the kitchen and bathroom. When the system senses a rise in humidity it automatically boosts the system to extract the air more quickly.
If additional heat is required there is a central heating system. Due to the construction and the amount of insulation, the house will hold the temperature much better than a traditional house.
With the lack of draughts in a HAPS home there will be no need to set the thermostat as high as if you were in a traditional house - but this will be down to personal preference. The Energy Saving Trust estimates that 1 degree lower on your thermostat will save £85-£90 per year.
Because of the construction of a HAPS home, it is likely that very little heating will be required to keep the home at a stable, comfortable temperature. Depending, of course, on how the home is used and how warm you like your home to be. A room thermostat works by sensing the air temperature and switching the heating on or off dependant on the thermostat setting.
The hot water cylinder provides all hot water needs on demand. It will heat only the water that is needed when the hot tap or shower is turned on.
The system prioritises hot water before heating. This is sensible because the constant heating approach of a HAPS home means that the requirement for hot water is likely to be more important.
The ventilation system is fully automated and does not need to be adjusted. The system will automatically go into boost mode when it senses an increase in humidity in the kitchen and bathrooms.
It is located in a cupboard which will need to be accessed for maintenance only. We will change the filters annually or as necessary.
The HAPS home only uses electricity. There are no gas appliances in the property.
Electricity bills can be reduced by turning lights off when not needed and through buying and using low energy appliances (see the energy rating label on the appliance). Things that are on constantly or used regularly are the most important such as fridges, freezers and washing machines.
Passivhaus is a performance-based set of design criteria for very low energy buildings, which can help create buildings that use around 75 - 90% less energy than standard.
Passivhaus design seeks to eliminate the need for space heating and is based on the principle that reducing heating loss to a minimum is the most cost-effective and most robust way of achieving a low carbon building. It relies on a simple 'tea cosy' effect maximising the use of insulation and air-tightness and the removal of thermal bridges.
By combining this with passive solar gain and mechanical ventilation and heat recovery systems, the design can create healthy and comfortable buildings that require minimal heating.
The Swansea Standard is a fabric-first approach, which achieves a 25% improvement on current building regulations. It relates to the thermal performance and air tightness of a building with the emphasis on the fabric of a home.
The fabric-first approach carefully considers the design and construction of the building envelope in the initial design stages, before any building work begins. By using high performing materials and adapting the principles of air tightness and ventilation, you can minimise the energy needed to heat your home - reducing running costs and CO2 emissions.
The building envelope is the physical elements separating the indoor environment from the outdoor. This consists of things like frames, structure and insulation in elements like walls, floors and roofs, and is important to maintain a comfortable indoor environment.
The fabric-first approach to build an efficiently sustainable home relies on the following different factors designed to minimise energy consumption:
- High-quality insulation
- Increased air-tightness
- Avoid thermal bridging
- Maximise solar gain
- Natural ventilation
The measurement of how efficient a building will be is the U-value, or thermal transmittance. Thermal transmittance is the rate of transfer of heat through a structure, divided by the difference in temperature across that structure. The units of measurement are W/m²K. The better-insulated a structure is, the lower the U-value will be = improved thermal performance, reduced energy costs and lower carbon-footprint.