What is a Passive House
The Origins of the Passive House
In 1988 Professors Bo Adamson of Lund University in Sweden and Wolfgang Feist from the Institute for Housing and the Environment in Germany developed the idea of the Passivhaus or Passive House. In 1990 they designed and built 4 Passive Houses in Darmstadt in Germany.
In September 1996 the Passivhaus Institute was set up in Darmstadt to help develop standards and improve techniques for building Passive Houses. Since then, over 25,000 certified Passive Houses have been built.
Principles of a Passive House
The main concept behind the Passive House is to design a house that does
not need to be ‘actively’ heated (or cooled) by a HVAC system such as
central air, hot water or gas. As with sustainable design and green
interior design, the motivation is to make environmentally friendly
houses that have a low carbon footprint and that reduce the use of
electricity to a minimum and thus reduce carbon emissions from power
The difference between a Passive House and a Zero Energy Building is that the Zero Energy Building does not seek to replace heating/cooling systems with alternative technologies. Rather the electricity for the house is generated from alternative energy sources such as photovoltaic panels. The aim of the Zero Energy Building is to make a building that produces more electricity than it consumes. The aim of a Passive House is to design a house that doesn’t need heating and cooling by heat pumps, furnaces, air-con units etc.
Passive Houses have worked very well in Central Europe and Northern Europe. Most of the certified Passive Houses have been built in Germany, Austria and Scandinavia. Typically, a passive House loses less than 0.5 °C (1 °F) per day (in winter), stabilizing at around 15 °C (59 °F) in the central European climate. This is an incredible achievement and obviously makes Passive House technologies key to formulating strategies for making buildings independent of fossil fuel energy.
Passive House in Germany
Read More About Passive House Technology
How Does a Passive House Work?
One of the key components to designing a Passive house is the use of
superinsulation. Superinsulation is what it sounds like – insulation of a
much higher specification than normally found in buildings. One of the
key components to Passive House construction is to build walls with much
bigger insulation gaps than normal houses. Much more insulation is
used. Although Passive Houses are normally built from scratch it is
possible to retro fit a house to conform to Passive House standards.
Insulation is also used in the roof and the gaps between the walls and the roof and the walls and the flooring are firmly sealed to prevent loss of heat. All holes for wiring, ventilation etc. are also carefully sealed to remove any holes where heat can be lost. Also the doors and windows are made with air-tight seals. Typically for a Passive House the walls are Rip40 and the roof is Rip60. These figures are measures of thermal resistance.
Another key component of superinsulation is the window design. Windows are made smaller and often use tree cover and awnings to reduce heat transfer. The windows themselves are triple glazed with a low e finish to further minimize heat loss/gain.
Instead of using standard HVAC equipment such as central air, air-con units, gas, hot water etc. a Passive House instead uses a dual purpose 800 to 1,500 watt heating and/or cooling element integrated with the supply air duct of the ventilation system. Normally the heater will not be used as the house is so well sealed and insulated that the waste heat given off from electrical appliances such as fridges, washing machines, light bulbs etc. combined with the body heat given off from the human inhabitants of the house is enough to keep the house warm.
It is, however, important to use electricity to keep the house properly ventilated. Because the house is sealed it is not easy for air to circulate around the house. Without air circulation the indoor air quality deteriorates. To solve this problem as efficiently as possible, using as little electricity as possible a heat recovery ventilation system is used. The heat recovery ventilation system has a heat recovery rate of over 80%. The system uses high-efficiency electronically commutated motors (ECM) to maintain air quality. When the weather permits natural ventilation is used such as a small opening or a more effective stack effect (smaller ingress and larger egress windows).
To power the heat recovery ventilation system photovoltaic panels can be put on the roof. Because the system uses much less electricity than normal HVAC systems and because it is often not used in the summer and spring the electricity generated can be deployed for running other electrical appliances. Often a Passive House will also use solar gain technologies to heat water.
Cost / Pros and Cons
A Passive House costs 14% more to build than a conventional house. The
extra expense is soon paid for by the huge savings to be made on heating
Passive Houses have performed excellently in the colder climes of Central and Northern Europe. Only a few Passive Houses have been certified in hot and tropical climates. Obviously in hot and humid conditions the challenges to the green designer are different. There is a danger of the insulation in the walls and roof becoming covered in mold. There is a house in Lafayette, Louisiana, USA, which is a certified Passive House The house uses Energy Recovery Ventilation instead of Heat Recovery Ventilation. This removes excess humidity and transfers excess heat to the hot water tank. Still much of the literature and technologies associated with Passive House design and architecture are concerned with replacing conventional heating not conventional cooling systems.
Finally, Passive House design tries to limit surface area and window size. Not everyone will be happy about living in a smaller house with small windows. Still overall, the Passive House is an impressive achievement and a testament to the efficiency of superinsulation. It is also a testament to how inefficient conventional homes are.
No comments yet.
- What are Green Roofs
A green roof refers to a roof that has grass, trees, shrubs and plants growing in soil on the roof. There are two basic types of green roof: intensive and extensive.
- The Dream of the Sustainable House
More about sustainable housing.
- The Importance of Re-Purposing
Imagine the world suddenly stopped producing new consumer items tomorrow. How would we survive? The answer is by re-purposing and upcycling.
- Water Supply Crisis
1.3 billion people have no access to clean water and 2.5 billion lack adequate sewage or sanitation. The demand for water doubles every 20 years.
- Whole Trees Architecture
Instead of cutting down trees and sending them off to be stripped and milled into planks Whole Trees Architecture design houses so the wood from a tree forms an integral part of the structure. All the tree is used.
- Are Feed-in Tariffs A Good Idea?
Since April 1st, 2010 people living in the UK are entitled to take advantage of a scheme that makes installing solar panels on your house or a wind turbine on your property much more affordable.
- Sustainable Flooring and Green Interior Design
If the principles of green interior design are looked at more closely it is obvious to see that sustainable flooring is key to the whole idea of creating environmentally friendly and people friendly interiors.
- How to Reduce Your Home Electricity Bills
The average family in the USA spends $2,200 a year on energy bills. A lot of these dollars are wasted. This article is about what you can do to reduce the waste in electricity use in your home.
- VOCs in the Home
One of the lesser known evil off-sprouts of the petroleum empire that has the planet at its mercy is VOCs or Volatile Organic Compounds.
- Green Cleaning: alternatives to normal detergents
What is not confined to poorer countries is the awful way we abuse the environment to get our clothes clean.
- Suberin in Cork Flooring
Cork is a renewable resource that makes excellent flooring. One of the reasons that cork is a good material for flooring is that it contains suberin.
- Notes on Sustainable Design
Sustainable Design is an all embracing philosophy that impacts on many different areas of human endeavour from architecture to agriculture.
- Earthmate Compact Fluorescent Light Bulbs
Demand for compact fluorescent light bulbs has lead to vast improvements in the design of CFLs and currently the best CFLs are made by Earthmate.
- Act Now To Stop Another Oil Spill Disaster
Watching the scenes of the devastating oil spill in the Gulf of Mexico has surely made many people realize the risks and hazards the world faces in maintaining its present addiction to oil consumption.
- Why Do So Many People Have Allergies
When I was a child I remember very few people had allergies or asthma. Now it seems everyone around me has either an allergy or asthma.
- The Cultural Significance of Trees
Trees endure for not decades but centuries and sometimes millennia. The pine called Prometheus in Nevada has endured for 5,000 years. Sarv-e-Abarkooh in Iran has stood for 4,000 years.
- Green Gift Ideas
It seems there is so many gifts to choose from and yet nothing really stands out. So why not try to buy earth-friendly products this year for the special people in your life?
- Bamboo is one of the Answers
Bamboo is strong, flexible and hard. It feels like a timber when it is towering above our heads but it is in fact a grass. It is the fastest growing grass on the planet.
- Planned Obsolescence
For many years big business corporations have tried unsuccessfully to keep secret a policy they have to build in a lifespan into their products.
More by this Author
A comparison between the Honeywell RTH7500D 7 day programmable thermostat and the cheaper Lux Products TX1500E Smart Temp Programmable Thermostat. This review is designed to help you choose the programmable thermostat...
A revealing insight into the difference between the two Thai islands of Koh Samui and Koh Phangan.
An article explaining the guiding principles of Green Interior Design and how it a discipline that is focused on ethics more than aesthetics.