Passive House

A passive house is a building in which comfortable interior climate can be maintained without active heating and cooling systems. The house heats and cools itself, hence the term "passive".

These are eco homes with highest energy standards.

A passive house has these features -

  • Compact form and good insulation.
  • Sun orientation with shading (see environmentally friendly houses).
  • Air-tightness of the building envelop.
  • Hot water supply using regenerative energy sources.
  • Energy efficient windows, glazings and frames.
  • Passive preheating of fresh air.
  • Highly efficient heat recovery from exhaust air.
  • Use of energy efficient appliances.

A Passive house is a comprehensive system. The term "Passive" describes the system's underlying receptivity and retention capacity. Working with natural resources, free solar energy is captured and applied efficiently, instead of relying predominantly on ‘active’ systems to bring a building close to ‘zero’ energy.

It is essential that the energy consumption is reduced to the maximum extent possible. If the energy consumed is less than a quarter of current consumption levels, the savings from conserved energy are enough to pay for the extra construction costs.

Normally, passive houses need about 80% less heating energy than conventional houses. The annual energy consumption for space heating does not exceed 15 kWh. The minimal heat requirement is fulfilled by heating the supply air in the fresh air ventilation system.

And the energy is supplied by renewable energy sources using non-mechanical methods, thereby optimizing natural resources.

These houses have a very low energy demand for maintaining interior comfort even in the winter season. The heating demand is so low that the environmental impact is negligible even if fossil fuels such as oil, gas or coal are used as heating sources.

The principle behind a passive house is based on the concept of reducing investment through energy efficient homes design. By dramatically increasing the energy efficiency of a building the heating, ventilation and air-conditioning (HVAC) systems can be radically simplified on reaching a certain level of efficiency.

The use of optimal daylight plays an integral role in passive energy systems. This involves the positioning and location of a building to allow and make use of the sun's rays throughout the whole year. By using the suns rays, thermal mass is stored into the building materials such as concrete and can generate enough heat for a room.

Extraordinary reductions in energy use and carbon emissions are made possible by the using energy efficient windows with high performance triple-glazing, super-insulation, an airtight building shell, limitation of thermal bridging and balanced energy recovery ventilation.

Energy losses are minimized. Any remaining heat demand is provided by an extremely small source. Avoidance of heat gain through shading and window orientation also helps to limit any cooling load, which is similarly minimized.

These guidelines should be considered while designing:

  1. Comfort should be kept at a high level. Passive Houses should be designed as comfortable homes for any region and for all climates. No solution can last which does not contribute to a better indoor climate.
  2. The solution should be simpler and more affordable than what is presently used in conventional buildings and contemporary technical systems.
  3. It is sufficient to minimize energy use with simple systems from conventional sources (see green home plans).
  4. Insulation is highly recommended in all climates.
  5. Shading is a must in all climates with high levels of solar radiation.
  6. Heat recovery is necessary in cold as well as hot climates if the external temperatures are often below 8°C or above 32°C.
  7. Using very low backup energy is an important precondition for passive house solutions.
  8. In many cases, the ground may be used as a heat or cold buffer.

It is a very well-insulated, virtually air-tight building that is primarily heated by passive solar gain and by internal gains from people, electrical equipment, etc.

An energy recovery ventilator provides a constant, balanced fresh air supply. The result is a system that not only saves up to 90% of space heating costs but also provides great indoor air quality.

Green Roof is used sometimes in passive houses. It is a partially or completely covered roof with plants or other vegetation. The covered roof creates insulation that helps regulate the outside temperature and controls how much goes in the building. It also retains water providing a water recycling system and provides sound proofing, which is ideal for noisy areas.

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Sushil Wadhwa

Sushil Wadhwa
Architect, Interior Designer, creator of Homes and Interiors... more.