An energy-efficient home is cheaper to run, more comfortable to live in and better placed for future regulations. In Cornwall, where many homes are off the gas grid and exposed to wind and rain, the case is especially strong. Whether you're building a new home or extending an existing one, this guide explains the main principles of eco building, the technology choices and the local policy points to be aware of.
Start with the fabric
The most effective approach is usually called fabric first. It means making the building itself as efficient as possible before adding heating or renewable technology. The key elements are:
Insulation. Well-insulated walls, roof and floor keep heat in. The type and thickness depend on the construction, such as timber frame, blockwork or structural insulated panels.
Airtightness. Draughts waste a surprising amount of heat. Careful detailing around windows, doors, service penetrations and junctions makes a big difference, and an air test shows how well it's been done.
Thermal bridging. Junctions between walls, floors and roofs can leak heat if they aren't detailed well. Good design reduces these cold spots.
High-performance windows and doors. Double or triple glazing with good frames, installed properly into the insulation line.
Orientation and shading. Positioning glazing to make use of winter sun while avoiding overheating in summer.
A well-built envelope reduces the size of heating system you need and keeps the home comfortable year-round.
Ventilation
As homes become more airtight, controlled ventilation becomes essential to manage moisture and keep the air fresh. Many low-energy homes use mechanical ventilation with heat recovery (MVHR), which supplies fresh air and recovers much of the heat from the outgoing air. For smaller projects, well-designed extract ventilation may be enough. Good ventilation also helps prevent condensation, which matters in Cornwall's damp climate.
Heating and hot water
With a well-insulated building, low-temperature heating systems work well. Common choices include:
Air source heat pumps, the most common low-carbon option for Cornish homes, particularly where there's no mains gas.
Ground source heat pumps, which can be very efficient but need space for ground loops or a borehole.
Underfloor heating, which pairs well with heat pumps because it runs at lower temperatures.
Government grants such as the Boiler Upgrade Scheme have been available towards heat pumps in some situations, but eligibility and amounts change, so check the current rules before relying on any funding.
Generating your own energy
Solar panels (PV) are a popular addition, and Cornwall gets some of the best sunshine levels in the UK. A battery can store daytime generation for use in the evening. Some homeowners also consider solar thermal for hot water, or an EV charger linked to their solar system. The roof design, orientation and any shading from trees or neighbouring buildings all affect how much a system can produce, so it's worth planning this at the design stage.
Materials and the Cornish climate
Sustainable building also means choosing materials that suit the setting and last a long time. Locally sourced stone and slate, responsibly sourced timber, and breathable materials on older buildings all help. Homes near the coast need finishes and fixings that cope with salt air and driving rain. For older solid-wall properties, insulation and other upgrades must be chosen carefully to avoid trapping moisture.
Planning policy in Cornwall
Cornwall Council has adopted planning policies on climate change and energy for new development, including a Climate Emergency Development Plan Document. For new homes, these policies can set expectations on energy demand and renewable energy, and an application may need to show how they're met. Building Regulations also set minimum energy standards, which are being tightened over time. Requirements change, so it's worth checking the current position with your designer and Cornwall Council early in the process. Our guide to planning permission in Cornwall covers the wider process.
Extensions and renovations
You don't need to build a new house to benefit. A well-insulated home extension can be built to a high standard, and a renovation is a good opportunity to upgrade insulation, windows and heating at the same time. Planning the upgrades together often costs less than doing them one at a time later.
Eco home FAQs
Is a heat pump suitable for an older Cornish home?
Often, yes, but the home may need insulation upgrades and larger radiators or underfloor heating to work efficiently. A heat loss survey is a good starting point.
Does building an eco home cost more?
Some elements, such as better insulation, windows and MVHR, can add to the build cost, but they reduce running costs over the life of the home. Costs vary from project to project.
What is fabric first?
It means making the walls, roof, floor, windows and airtightness as efficient as possible before adding heating or renewable technology.
Talk to us about sustainable building
Cornish Building Company delivers sustainable building and eco homes and new builds across Cornwall. Call us on 01208 816991 or contact us to discuss your project.
