10 May 2023, 14:04
By Steven and Tamsin Bryan
With Climate Change being high on the agenda and energy prices rocketing, it has never been more important for new builds to be ‘Carbon Neutral’. In the past being Carbon neutral has been seen as an expensive, luxury option however as the drive towards ‘Net Zero’ gathers pace it is now essential and not that difficult to achieve.
Steven and Tamsin Bryan at their carbon neutral home in High Bickington, England (top). The home received a 100+ Sage Score. In April 2023 it was listed for sale on Realty Sage by real estate agent, Daisy Layland, eXp World UK Limited-North Devon Bespoke Estate Agent. (bottom)
10 Top Tips to Build a Carbon Neutral House
All of these factors need to be considered from the very beginning, even before a shovel has been put into the ground. Retro fitting any energy saving technologies is more costly and difficult than planning them at the start. Whilst many of these technologies have a large initial outlay, the cost and carbon savings mean they will pay for themselves rapidly. (eg 13.2kW solar PV + 10.4 kW storage cost £16k produces over 22000kW / year at current costs the system will pay for itself in 2 years.)
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- Insulation is key – it is more carbon (and cost) effective to prevent heat loss even when using the most carbon friendly heating. Walls, floors and roofs all need insulation to pass building regulations but use the best insulation you can afford – rigid insulation is twice as effective as the same thickness of mineral wool in wall and roof build ups. Use more insulation and reduce the air gap in a cavity wall and use thermal blocks as the inner leaf.
- Consider roof build ups. A ‘warm roof’ with reflective blanket insulation completely wraps the roof and is highly effective when used in conjunction with other insulation below such as rigid insulation between rafters or a high quality insulated plasterboard below rafters.
- Insulate between internal floors and stud walls. This helps trap heat in individual rooms where you most need it. Solid internal walls can be composed of thermal blocks where appropriate.
- Triple glazing is worth the extra cost – especially if your design has a large amount of glass. Some companies may offer triple glazing for the price of double and if one company is supplying the complete glazing envelope, negotiate with them.
- Keep an eye on workmanship. All rigid insulation and reflective blanket joints should be thoroughly sealed with aluminium foil tape to prevent air leakages. Window fittings should be thoroughly sealed to minimise air / heat loss. Make sure all junctions are properly sealed.
- Be aware of air permeability / pressure testing. All new builds should have an air pressure test to measure leakages. This can have a large impact on the EPC as a ‘leaky’ house will leak heat.
- Ventilation needs to be factored into your design. This is needed to avoid condensation build up - MVHR works well but uses electricity and this would need to be offset in some way. At the design stage look at all options. In some rural / open areas ‘purge’ may be an option and needs to be considered in your glazing options. Tilt and turn windows or windows with a ‘night ventilation’ feature may be appropriate.
- Heating options. Air source and ground source heat pumps rely on electricity but as this can be generated sustainably, they are considered carbon friendly. If you have space, Ground Source Heat Pumps are more efficient than Air Source Heat Pumps. Both work best with wet system Under Floor Heating but can be used with specialised low temperature radiators. BioFuel is also considered carbon neutral as although the burning of the fuel does emit carbon, that is offset by the carbon that is taken up by the growing of the vegetation (timber / arable) used in the fuel. You will need space for the biomass boiler and storage of the fuel so consider whether you have adequate space. Ensure that your heating design has both time and temperature zone controls.
- Direct Hot Water (DHW). Heat pumps and most biofuel boilers supply water via a cylinder. Aim for a highly insulated cylinder and make sure all pipework is fully insulated to reduce heat loss. There are some cylinders on the market that use F-Gas to take the ‘waste’ heat from the operation of the heat pump and uses it to boost the water temperature in the DHW cylinder, reducing costs.
- Generate you own electricity. Solar PV with battery storage is increasingly effective (you could also look into a wind turbine if you are in an appropriate area). Most Solar PV systems overproduce on the summer months, so the excess can be fed into the National Grid. Whilst you do get paid for this it is not anywhere near what you pay for electricity! Depending on the heating system you have chosen, you may need to import some electricity in the winter months, but if your Solar PV has been designed correctly you should produce more than you use across the year, thus offsetting any carbon emissions.