It has been estimated that buildings are responsible for 40% of global carbon emissions. Given the ongoing climate crisis, the need to address this has never been greater. One way of doing so is by making your property energy efficient – in the UK, 14% of emissions come from energy use in our homes, and in 2017, consumption actually increased. There are several ways to go about building an energy efficient home and the payoff is not only environmental but will save a lot of money on bills.
Energy efficiency is not just about using sustainable materials and building techniques but constructing your home in a way that cuts energy consumption in half over your over the property’s lifetime. Investment in good design, choosing the best fabric solutions, and installing an appropriately sized heating system are all crucial steps.
Thermal bridging
Central to energy efficiency, a thermal bridge occurs where the insulation of an element is compromised. This happens at junctions, where walls meet floors or roofs, or around openings, doors and windows - and it’s not uncommon for a new build home to contain hundreds of defects.
A solution is to build parts of the home in a factory. With a diminishing number of skilled trades in the UK, modern methods of construction use off site solutions to control quality, improve tolerances and eliminate the energy performance gap. This type of innovation is often considered a risk, but sourcing and relying on traditional trades to deliver an energy efficient home is a risky option as well.
Airtightness
Airtightness is about eliminating unwanted ventilation in buildings, typically draughts around openings and junctions, and it is crucial to get it right at the outset. Houses are made up of lots of incompatible materials so there is a need to interface blocks, timber, insulation and concrete, as well as doors and windows, and that takes a high degree of skill, as these may expand and contract at different rates once the house is heated up.
Insulation
Insulation is critical to achieving Building Regulations, but also will determine the long-term running costs of the house. We advise looking for an optimal thickness level and ensuring that you have high quality installation, as any gaps will seriously affect performance.
Lightweight properties can be prone to overheating, in which case you should introduce thermal mass through a solid floor or solid internal walls to help manage temperature extremes. The thermal mass acts as a passive store, so on hot summer days the building keeps cooler, and in the winter the thermal mass keeps a minimum temperature that can then be topped up by a few degrees to achieve the comfort level required.
Solar thermal and PV panels
Once you’ve built an excellently insulated and airtight building, heat loss can be so small that a traditional heating system would be oversized. Once this need for heating is minimised, hot water becomes the primary demand, so using a cheap and established technology such as Solar Thermal panels can provide hot water across many months of the year, significantly reducing costs. PV panels are not currently subsided through a feed-in-tariff, but integrated PV roofs in various finishes are available to reduce the overall running costs and carbon emissions of the home.
People are increasingly having a say in how their property is built and it’s crucial that they appreciate lifecycle, while having an open mind about offsite construction. To help builders and customers identify what good looks like, BRE has developed the Home Quality Mark, which covers all aspect of a home, environmental social and financial. To provide confidence in buying an off-site fabricated home, BRE has also developed a product standard BPS 7014 to provide confidence in the off-site systems and products being introduced.
