An energy efficient building makes sense, says Gareth Boyd from 2020 Architects, as he offers some self-build tips to help save those pennies and the planet.
1/ Don’t pass on Passivhaus principles
If you want to make your self-build energy efficient, do some research on the aims and principles of Passivhaus. In short, the aim of Passivhaus is for a building to consume as little energy as possible by getting the most out of the fabric of the building. This ‘fabric first’ approach considers drastically reducing air leakage, increasing insulation, making best use of solar gain and using technology such as a Mechanical Heat Ventilation Recovery (MVHR) system to create as tight an envelope as possible. As modern architects these elements inform all of our designs as sustainability is one of our guiding principles.
2/ Keep it tight
Make your building as airtight as possible as it is the most important step to achieving an energy efficient self- build home. This means stopping air escaping from the building through cracks and gaps in the external envelope. Construction, specifically the materials that you use for the frame and walls of your building, alongside a high quality build are what matter most here. Any combination of timber frame, brick and block, structural insulated panels, insulated concrete formwork and cross laminated timber are efficient construction methods for ensuring a high level of air tightness in your building. They can be boosted by adding special tapes and membranes. An MVHR system is a really useful option for ventilation and heating a sufficiently airtight home.
3/ Wrap it up
While the construction is important, it must be paired with super high insulation. An airtight and well-insulated building will keep the heat energy inside, the temperature will stay higher and the heating costs lower. Insulation works by stopping heat energy from leaving a building. Really high-level insulation should make it as hard as possible if not impossible for the heat energy to find its way to colder surfaces reducing the risk of it getting lost through the transfer of heat. There are lots of products that you can use to achieve a high standard of insulation, sheep’s wool, mineral wool or phenolic foam are good high quality options with good thermal resistance.
4/ Glazing, orientation and solar gains
It is a balancing act to get the most from solar gains, which are the sun’s contribution to a building’s internal heat. Glass is great at allowing the sun’s heat energy to pass through but it is a very poor insulator and loses heat quickly when the sun disappears. Aim for enough glass to benefit from as much of the sun’s free heat and natural daylight as possible but not so much that it overheats your building in summer or loses too much of the internal heat in winter.
The orientation of your building will determine how much sunlight your building receives. Ideally any windows used for maximising solar gain should face south or as close to south as possible. Overheating is becoming a more common problem with the increased use of glass in modern designs although adding solar shading to your design can reduce this. North facing surfaces receive very little to no sun so it is best to keep glazing on this side of the building to a minimum.
5/ Technology rewards
To be energy efficient consider the use of available technologies to heat and power your home. Solar photovoltaics are panels that can be installed onto an existing roof to capture the sun’s energy using photovoltaic cells and convert it to electricity. Interestingly, they do not need sunlight to work and energy is still generated on cloudy days. It can be used to run appliances and lighting in your home. The UK government’s feed-in tariff scheme rewards you for the electricity you generate even if you don’t use it. You also have the option to sell any unused electricity back to the grid.
Another way to heat your home is through the use of heat pumps; these work by extracting heat contained within earth, air or water, depending on which system you choose. Air source heat pumps are reasonably straightforward to install, making them cheaper than ground or water source options.