Passive and Low Impact Heating Systems

Passive and low impact heating systems vary slightly depending upon the intensity of the climate zone for a building:

1 In a cold climate pass incoming fresh cool air over a heat source such as a fireplace, floor with heat storage capacity, or heated wall such as a Trombe wall;

2 Incoming cool air can be forced with small low cost fans. This creates a positive pressure in a building and forces cold draughts out of a space. In a cold climate this keeps cold draughts from intruding and forces a heat stop at tight gaps around openings when combined with a fan entry pump. This also introduces warmed fresh air to a building which is essential for healthy living and to limit mould growth;

3 A glazed heat chimney which goes above the highest point of a building and used to expel hot air in summer can be closed in winter with adjustable louvres and a low cost fan can force hot air to the lower levels and create warm convection currents;

4 A concrete slab with sun heating can radiate warmth at night. A wall with large solar mass stores heat and can radiate the heat into a room, eg water fill bottle "Trombe wall". Glazing requires shielding at night with thick curtains with pelmets;

5 Thick curtains with pelmets stop the movement of air over cold glazing and lessens the convection cooling on the room;

6 A vestibule which acts as an airlock and coat room protects the main building from draughts when an external door is opened;

7 Double glazing, triple glazing, gas between layers of glass, weather strips are all relatively low cost ways of reducing heat loss in a building;

8 Building shape also affects heating requirements. In very cold climates more of a square shaped building with a central heat source reduces the cost of heating. A warmed basement also heats storeys over;

9 Heat exhangers are a low cost way of transferring heat from outgoing air to the incoming air and raise the temperature of the incoming air by a number of degrees;

10 More active heat sources are refrigerant lines buried around a building and taking heat from the ground and warming the inside of a building;

11 Heaters at a low point in a room assist the convection heating process. Skirting height heaters are common in very cold climates;

12 Thick insulation layers in roofs, walls, and floor reduce heat loss and reduce draughts. Beware of puncturing insulation layers with holes from lights, eg down lights. If downlights are used consider carefully insulating the space above the downlights while not creating a potential fire source;

13 Doorways stop heat transfer at the wall above doors because hot air. Having full height doors from floor to ceiling allows additional heat to pass through openings when doors are open. Another option is to have vents above doors to the celing. A ceiling fan can blow warm air down to warm lower room areas and to help force warm air through openings;

14 Thermal mass in walls provides a time lag between the day and night time temperatures. This is particularly useful in desert climates where days can be hot and nights cold. The warmth stored in a wall radiates during the colder night warming the building. However this effect should be avoided in humid areas where slow heat transfer on a hot humid night is generally uncomfortable.  

15 A solar heater can provide heat to the inside of a house. Please see the Sunlizard data from a solar heater/cooler installed in a house in Sydney.  The heater works by heating air in a similar device to a solar hot water heater mounted on the roof of a house. The air is circulated by fans run off photovoltaic cells mounted on the roof near the air heater. See the Sunlizard home page.