BACK-UP HEATING
Does a Passive House need a heating system?
Yes. Sometimes you will find definitions of a Passive House as a building that doesn’t need any heating, but that is simply not true. You need what is referred to as a ‘back-up’ heating system, which is tiny in comparison to that required for a conventional house.
What kind of heating system is typically used in a Passive House?
Typically any additional heating required is delivered using the mechanical ventilation system. The air passing around the house can be heated using a variety or combination of means whether electrical-based (such as with a heat pump) or using a pellet-boiler and / or solar panels. It is not usual to find (or indeed need) radiators or underfloor heating in a Passive House. If you really would like such systems, then of course they can be used. Be aware that in doing so, you are ‘doubling up’ the amount of services in your house, which will, in turn, increase the cost of construction.
Can I control the temperature in my Passive House?
Yes. A passive house is designed to deliver 20 degrees Celsius throughout the entire dwelling right throughout the heating season while using the minimum amount of energy. If you are a ‘hot house flower’ and prefer on occasion to have warmer temperatures, then your system should be designed so that you can ‘turn up the heat’, typically controlled using a conventional room thermostat. It’s your house, and you choose what temperature you like. It will often happen in a passive house that the temperatures upstairs will be slightly cooler (perhaps one degree C, for example) than downstairs. This can be as a result of the greater activity downstairs during the day (cooking, watching TV, lounging) compared to upstairs. Most people find this slight difference quite welcome, finding it more comfortable to sleep. You can if you wish design your Passive House to deliver specific pre-determined temperatures in different rooms, but this will probably require a more complex system and increase your costs. In the MosArt Out of the Blue house it has often been necessary to cool the house in winter for example at Christmas when there might be several guests visiting. There’s a really high tech solution to this problem, open the window!
Can I have an open fireplace in a Passive House?
Sorry, but the answer in this case is No. Having an open fireplace would dramatically reduce the efficiency of the mechanical heat recovery ventilation system (due to lack of airtightness). Furthermore, the open fireplace would introduce major drafts to the house as well lead to huge heat losses. However, there are other really clever means of having a real flame effect in your Passive House, including bio-ethanol fires as well as wood burning boilers or stoves with glass fronts. By the way, if you have young children in the house, please reassure them that Santa Claus knows the Passive House standard very well and he uses the ventilation system and some magic dust to bring the gifts into the house.
Will the house cool down if it is unoccupied and ‘unheated’ for a period in the winter?
Yes, but only marginally and nothing as dramatic as with a normal house. Due to the high levels of insulation and draft-proofing in a Passive House, the heat loss in such a situation will be minimal (perhaps 2 to 3 degrees Celsius depending on duration and weather).
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