Passive solar heating can even out day and night temperature variations

Passive Solar Heating

On average 39% of energy consumed in Australian homes is for space heating and cooling. Designing for passive solar heating can reduce this burden. Passive solar heating is basically allowing the winter sun into the building and trapping that thermal energy withing the fabric of the building.

Passive Solar Heating
Open Plan Kitchen in Kelmscott

Careful consideration should be given to the following:

  • Northerly orientation of daytime living areas.
  • Appropriate areas of glass on the northern facades.
  • Shading of glass.
  • Thermal mass for storing heat.
  • Insulation and draught sealing.
  • Floor plan zoning based on heating needs.
  • High performance glazing where required.

Passive solar heating works by trapping solar radiation by the greenhouse action of correctly oriented windows exposed to full sun.
Trapped heat is absorbed and stored by materials with high thermal mass, such as bricks, concrete, rammed earth, and stone inside the house. It is re-released at night when it is needed to offset heat losses to lower outdoor temperatures. It effectively evens out day and night temperature variations.

Thermal mass should be located predominantly in the northern half of the house where it will absorb most passive solar heat. You could consider the use of low thermal mass materials such as timber frame construction and high levels of insulation in south facing rooms.

Daytime living areas should face north. Ideal orientation is true north and can be extended to between 15° west and 20° east of north.

Bedrooms require less heating and can be located on the southern side of the house, but this can vary depending on preferences for northern or early morning eastern sun.

Bathrooms, laundries and garages again require less heating and can be located to the west or south west to act as a buffer to hot afternoon sun and cold rain bearing winds, or to the east and south east.

Compact floor plans minimize external wall and roof area, thereby minimizing heat loss.

A balance should be achieved between minimizing heat loss and adequate day lighting and ventilation.

To assist with the distribution of heat you could consider heat shifters. This is a fan and ducting system, costing little to run and install, which moves air from warm areas to cooler areas.

Heat shifters can also redistribute warm air that collects at the ceiling back down to floor level

Passive solar heating can dramatically reduce energy costs.