Frequently Asked Questions on Passive Houses

What is a Passive House?
What are the key components to a Passive House?
What is Air Tightness?
What is a Thermal Bridge?
What is Thermal Imagery?
What is Heat Recovery Ventilation?
What is the difference between a Passive window and a standard window?
What is a U-value?
Is it profitable to build a Passive House?
Can I build a Passive House using either blocks or timber frame?

What is a Passive House?A Passive house is a building in which a comfortable interior climate can be maintained without active heating and cooling systems.

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What are the key components to a Passive House?
The key components which need to be included when building a Passive House are;

- Orientation (preferably south facing)
- High Quality Insulation
- Ventilation with heat recovery ( >75%)
- Passive House Windows
- Air Tightness (<0.6 air changes per hour)
- Cold Bridge Elimination.

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What is Air Tightness? Air tightness measures the amount of air flow entering and leaving a building. Air loss can occur through gaps and cracks in the fabric of a building. The method used to establish the level of air loss within a building is called the blower door test. Air tightness testing and thermal imaging will identify and highlight the areas within a building where heat is escaping.

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What is a Thermal Bridge? A thermal bridge is created when materials that are poor insulators come in contact, allowing heat to flow through the path created. Insulation around a bridge is of little help in preventing heat loss or gain due to thermal bridging; the bridging has to be eliminated, rebuilt with a reduced cross-section or with materials that have better insulating properties, or with an additional insulating component a thermal break.

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What is Thermal Imagery? Thermal imagery is used to identify any patterns of heat loss within a building that are not clearly visible by either the naked eye or from the blower door test. A high tech infrared camera is used in this test of air tightness.

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What is Heat Recovery Ventilation? Heat Recovery Ventilation reclaims the heat from warm exhaust air exiting a building, and pre-heats fresh air entering a building. In a Passive house, it is most common for this to take place beneath the ground through air ducts.

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What is the difference between a Passive window and a standard window? Windows within a Passive house play an important role by reducing the heat loss out of the house. Passive windows are super insulated and trap solar gains within a building. All Passive houses require triple glazed windows to ensure the correct U-value is achieved.

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What is a U-value? The U-value is the measurement of which heat is lost through an area of a house. The lower the U-value, the better. It means your house will be more comfortable and warm inside and less energy will have to be used to replace this lost energy.

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Is it profitable to build a Passive House? A Passive house is profitable to build as its life cycle costs are greatly reduced, comfort levels are raised to a much higher level, indoor air is healthier for all occupants living in the house due to the lower particle count. The ever increasing energy costs for heating the house will not be an issue for the occupants of the house.

Research conducted has proven that a Passive house will cost 10% of the normal standard house energy bill.

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Can I build a Passive House using either blocks or timber frame? Yes, is the answer. At Passive House Builder Ltd. we build using blocks, timber frame and (ICF) insulated concrete forms. We believe in offering our customers a choice. We can assist you in making this decision, if you are unsure.

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