The Resilience of Passivhaus Homes in Power and Heating Cuts

The key to a Passivhaus home’s comfort during power and heating cuts lies in its exceptional construction. 

Developed in Germany in the 1990s, Passivhaus is recognised as the world’s leading low-energy building standard. 

Passivhaus homes are packed with higher quality and far greater levels of insulation than average new builds. The insulation wraps the home like a thermal blanket, reducing heat loss in winter and keeping the interior cool in summer.

Passivhaus homes are airtight, with no gaps for cold draughts to seep in and warm air to leak out. This is achieved through the use of a continuous air barrier that envelopes the entire building – from the walls and roof, to the floors and openings. The design process identifies all potential air leakage paths. During construction, even the smallest of these gaps are sealed using specialist tapes and adhesives. Anywhere an air leak could occur, Passivhaus makes the extra effort to plug it.

High performance triple glazing comes as standard. The spaces between each pane of glass are filled with Argon gas, which functions as an acoustic and thermal insulator. It reduces outdoor noise, prevents cold glass surfaces and eliminates condensation – warding off mould growth and keeping the atmosphere in your home a healthy one.

The bulk of the home’s heat is supplied by ‘passive’ sources, including sunlight, the body heat of occupants and electrical appliances (i.e. boiling the kettle and watching tv). These are converted into efficient, usable energy.

Storm Darragh was the fourth serious storm to hit the UK since mid-October. Experts warn that climate change will bring “more frequent and extreme weather”, increasing the risk of prolonged power and heating outages.

 A study by UK Power reveals cuts are becoming increasingly common for households, whether caused by severe weather, high energy demand, or faults in the electricity network. These outages disrupt heating, cause emotional strain and make daily life difficult, highlighting the urgent need for new homes to be future-ready and resilient. 

Thankfully, the Passivhaus standard provides a tried-and-tested solution. As demonstrated by Tomás's experience, homes built to this standard remain comfortable for extended periods during power outages or heating system failures. Even in severe cold, Passivhaus homes can provide a safe, habitable environment for up to a week.

In 2023, the International Passive House Association conducted a technical study using simulations to compare how homes perform during a heating system failure. This study examined three types of homes under the following scenario: heating is cut for seven days in late January, with outside temperatures plummeting to -13°C. Electrical appliances and the ventilation system remained operational.

The study compared:

• An old home
• A Passivhaus
• A home built to Germany’s low-energy building standard, the Energy Conservation Ordinance (EnEV)

The living rooms in all three homes began at a temperature of 22°C. Once the heating was turned off, the following was observed:

A similar study in Norway (2021) explored how homes in Oslo coped with a four-day power outage starting on the 14th January – statistically the coldest day of the year. Two types of homes were tested, both with and without solar panels and battery storage:

• A home built to Norway’s TEK17 standard, one of the world’s strictest low-energy building standards
• A Passivhaus

The living rooms in each home began at a temperature of 21°C. After the power was cut, the following occurred:

Passivhaus homes are more than energy-efficient; they are a resilient solution to the challenges of a changing climate, ensuring comfort and safety even in the most extreme conditions.