The price cap will rise by £63 in October, the third increase this year. Against that backdrop, a new eco home in Dorchester, Dorset, offers a glimpse of what an EPC A+ property actually looks like, not in a glossy brochure but in timber frame, triple glazing, and a heat pump.
As reported by e-architect, the house was designed by a local firm and built to Passivhaus principles, super-insulated, airtight, and mechanically ventilated. Solar panels on the roof feed a heat pump. The result is a home that uses roughly 90% less heating energy than a typical 1930s semi.
Who qualifies, and who doesn’t
This is a new-build, not a retrofit. That matters because the economics are different. Building a Passivhaus from scratch costs roughly 5–10% more than a standard build, according to the Passivhaus Trust. Retrofitting an existing home to the same standard can cost two to three times that premium, and few UK homes have the cavity walls or roof space to hit A+ without major work.
But the principles transfer. A typical 3-bed semi with solid walls, single glazing, and a gas boiler uses about 12,000 kWh a year for heating. The Dorset home, by contrast, would use under 1,500 kWh. Even a partial retrofit, loft insulation to 300mm, cavity wall fill, double glazing, can cut that to 8,000 kWh, saving roughly £400 a year at current prices.
What it costs a typical 3-bed semi
Ofgem data shows the average household on a standard variable tariff will pay £1,568 a year from October. A home with EPC A+ could halve that. The catch is the upfront cost. Solar PV installation runs £5,000–£8,000 for a 4kW system. A heat pump costs £7,000–£13,000 after the Boiler Upgrade Scheme grant of £7,500. Triple glazing for a semi is £4,000–£7,000.
The Energy Saving Trust estimates that a fabric-first approach, insulation and airtightness before renewables, delivers the best payback. Loft insulation alone costs £300–£500 and saves £180 a year. Cavity wall insulation is £500–£1,500 and saves £190 a year. That’s a payback of two to eight years, far faster than solar or heat pumps.
What this misses
The Dorset home is a showcase, not a template for every street. Most UK homes are not timber frame; they are brick cavity or solid stone. Airtightness levels below 0.6 air changes per hour, the Passivhaus standard, require careful detailing that most builders don’t offer. And the grants available for new-builds (like the Future Homes Standard) are not the same as for retrofits.
But the direction is clear. From 2025, all new homes must meet the Future Homes Standard, which effectively bans gas boilers and mandates heat pumps or district heating. Existing homes will follow, with EPC C minimums for rentals by 2028 and for all homes by 2035. The Dorset home is a proof of concept: it can be done, and the technology works.
What to do next
Households on standard variable tariffs can check eligibility for the Boiler Upgrade Scheme through gov.uk from 1 November. Applications for ECO4 insulation grants run until March 2027. For new-build buyers, ask your developer for the SAP rating, anything above 85 is good; above 90 is excellent. The Dorset home’s A+ rating is 100+.
Frequently Asked Questions
It's possible but expensive. Most UK homes can reach EPC B or C with insulation, solar, and a heat pump. A+ typically requires Passivhaus-level airtightness, which may involve structural changes. A professional energy audit costs £200–£400 and will show your ceiling.
Passivhaus Trust figures suggest £1,800–£2,500 per m² for a new-build, compared to £1,500–£2,000 for a standard build. The premium is 10–20%, but energy bills are 75–90% lower.
