Passive House is a building standard. A house that stays at a comfortable temperature through the year, has clean air and quiet rooms, and costs very little to heat or cool. Every HausGrid home is designed and certified to the Passive House standard.
Most houses lose heat as fast as you put it in. A Passive House keeps it.
The easiest comparison is a thermos flask. There is no heater inside a flask; it just holds whatever temperature you put in it. A Passive House is built on the same idea. The walls, roof, floor and windows are so well insulated, and so carefully joined, that the sun coming through the windows, the people in the rooms and the appliances running are enough to keep the house comfortable for most of the year.
On the coldest and hottest days a small heating or cooling system tops it up, but it runs far less than in a normal house. Fresh air comes in through a ventilation unit with a filter, instead of through gaps under doors and around windows, so the air indoors is cleaner than in most homes and you never have to choose between fresh air and a warm room.
Where the name comes from. "Passive" refers to the building doing most of the work on its own, rather than relying on equipment. The standard was defined in Germany in the early 1990s and there are now certified houses in every European climate, including Portugal.
What you notice when you live in one.
You will not see the insulation or the airtight layer. What you get is a house that is comfortable, healthy and cheap to run.
Comfort, all year round
Every room stays at a comfortable temperature, in January and in August, and you rarely have to adjust anything.
No cold floors, no cold corners, no bedroom that overheats under the roof.
In winter the walls and windows stay close to room temperature, so you can sit next to a window without feeling the cold coming off it.
In summer, external shading and a heavy, well-insulated shell keep the afternoons cool. Air conditioning is there as a backup, not for daily use.
The temperature is stable enough that most people stop thinking about heating and cooling altogether.
Health and well-being
Filtered air, quiet rooms and no damp. The most common comment from people who move into one is that they sleep better.
Incoming air passes through a filter that takes out pollen, dust and most of the fine particles from traffic.
Used air, cooking smells and humidity are extracted from kitchens and bathrooms around the clock, so the house does not get stuffy.
The same insulation, triple glazing and sealed shell that keep the heat in also keep road noise out.
Mould needs a cold surface and trapped humidity to grow. A Passive House has warm surfaces and constant ventilation, so it has nowhere to start.
Lower bills
A house that holds its temperature needs very little energy to keep it there, and the bills reflect that.
The standard sets a fixed limit on how much energy a certified home may use for heating and cooling. It is a small fraction of what a conventional house uses.
On a cold day, the heat output needed for the whole house is about the same as one hairdryer.
Because the demand is so low, the heating and cooling equipment is small and does not need much maintenance.
The certificate documents the performance, which also matters when you come to sell.
How it works
Six things, done properly.
A Passive House looks like any other house from the outside. The difference is in six parts of the construction, each built to a much higher standard than usual. Hover or tap each one to see where it sits in the building.
Built for the South European climate, not just for the cold.
Because the standard started in Germany, people sometimes assume it is only about keeping warm. In the south of Europe the conditions are different: mild, damp winters and bright summers. The standard covers both, and the design of each house is adjusted to the site.
Winters without the chill.Many Portuguese houses are colder inside than outside on a winter morning. A Passive House keeps the warmth from the previous day, so it is comfortable when you get up without a heater having run all night.
Summers without a fight.External shading on the south-facing glass, ventilation at night and a shell that warms up slowly keep the house cool through the afternoon. Air conditioning is available but rarely needed.
Humidity under control.Sea air and mild winters make damp a common problem in older coastal houses. Constant ventilation keeps indoor humidity down, and because the junctions stay warm, condensation does not form on them.
Wood, stone and cork.The homes are built from natural, low-carbon materials, with timber panels made to industrial precision. Wood feels warmer to the touch than concrete and handles humidity better than synthetic materials.
Designed to the standard. Certified against it.
Why "certified" is the word that matters.
Many houses are described as "built to Passive House principles". That describes an intention. Certification means an independent certifier has checked the design and the finished house against the standard and confirmed that it meets it.
Modelled before it is built.The whole house is calculated in detail against the standard's limits for heating, cooling, summer overheating and airtightness before construction starts.
Tested when it is built.The completed shell is pressure-tested with a fan. If more air leaks than the standard allows, the house does not pass.
Documented for you.The certificate records what was designed, what was installed and what was measured on site.
Every HausGrid home is designed to the Passive House standard and certified against it.
Common questions
Things people ask before they live in one.
Yes, whenever you like. The ventilation system means you do not have to open them to get fresh air, which is useful on a cold or rainy day. On a summer evening, opening the windows to cool the house down is part of how it is meant to work.
No. Fresh air is supplied to bedrooms and living rooms all the time, and used air is extracted from kitchens and bathrooms. People usually notice the house feels fresher than others, particularly first thing in the morning.
No. It is a performance standard, not an architectural style. A Passive House can be any shape or finish. The difference is in the construction, which you cannot see once the house is finished.
Yes, but the system is small and runs only during the coldest weeks and the hottest afternoons.
No. There are certified Passive Houses in Spain, Italy, Greece and Portugal, and the standard sets limits on summer overheating as well as winter heating. On the Portuguese coast the design relies on shading and night ventilation as much as on insulation.
A filter change a couple of times a year. It uses very little electricity and runs more quietly than a fridge.
