How this 1960s house stays cool without air conditioning
Passivhaus standard reduces energy consumption by up to 90%.
1What is Passivhaus?
Passivhaus is a building standard developed in Germany 35 years ago. Its core principle is maintaining constant indoor temperature through airtight insulation. These homes save up to 90% energy compared to conventional houses. Marion Baeli's 1960s ex-council house was retrofitted to this standard. Even during heatwaves, the interior remains 10°C cooler than outside, mimicking air conditioning effects without the energy use.
2The retrofit process
When the Baeli family moved in a decade ago, the house had poor insulation and drafty PVC double-glazing. Phase one involved insulating shared walls, floors and roof while eliminating thermal bridges (structural weak points for heat transfer). Phase two replaced cavity brick walls with super-insulated timber frames and installed triple-glazed windows. The £5,000 air-tightness work was among the most cost-effective measures.
3Mechanical ventilation system
With the house completely airtight, a mechanical ventilation system with heat recovery was installed. It filters incoming air while recovering heat from exhaust air, ensuring fresh circulation without energy loss. In winter, just one radiator now suffices to heat the four-bedroom, three-storey home. The system maintains air quality while preventing the temperature fluctuations that drive energy consumption.
4Costs vs savings
The total retrofit cost £80,000, with windows being the most expensive item at £30,000. However, Baeli calculates an 88% reduction in energy demand, saving £750 annually. She spread the project over 10 years to manage costs. According to the Passivhaus Trust, incorporating these standards in new builds adds just 2-5% to construction costs, making them far more affordable when planned from inception.
5Daily temperature management
Baeli keeps windows and curtains closed during daytime, using dust sheets in her garden to shield windows from direct sunlight. At night when outdoor temperatures drop, windows open to cool the house naturally. However, during June 2023's heatwave when nighttime temperatures stayed at 27°C, the house reached its highest recorded internal temperature. In such extreme cases, limited air conditioning might become necessary before Passivhaus measures can maintain comfort.
6UK regulatory changes
The Future Homes Standard coming in March 2024 will impose stricter energy performance requirements for new English homes, moving closer to Passivhaus principles. Scotland is consulting on equivalent building regulations that may publish next year. Major developers like Barratt Redrow are already constructing Passivhaus-compliant affordable housing in London, complete with heat pumps for temperature control.
7Climate change context
Over half of UK homes currently risk overheating, projected to rise to 92% by 2050 at current climate change rates. Summer 2023 saw five heatwaves, becoming the UK's hottest on record. Solutions like Passivhaus prove critical for climate adaptation. While retrofitting existing stock is expensive, the technology offers a blueprint for resilient housing as extreme weather events increase in frequency and intensity.
8Future housing vision
Baeli's home demonstrates how individual actions can mitigate climate impacts. Though retrofit costs are significant, long-term energy savings and comfort justify the investment. The construction industry is adopting such sustainable solutions to stay ahead of tightening regulations. Passivhaus standards are increasingly becoming the norm for new builds, pointing toward a future where homes actively contribute to emissions reduction rather than exacerbating the problem.
Original article: BBC News — 1960'lardan kalma bir ev nasıl klima olmadan serin kalıyor?