passive solar design principles

We are all aware of how important it is to nurture nature… to look after the environment, but did you know that you can do this and save money?

Passive Solar designed homes can achieve this through the efficiencies of their design – allowing the use of the sun’s thermal energy for the natural heating and cooling of living spaces.

Utilising this approach, the building itself – or some element of it – takes advantage of natural energy characteristics in materials to create the optimal ambient temperature using the sun as its source. Passive Solar systems are simple, have few moving parts, and require minimal maintenance… often requiring no mechanical systems at all.

Operable windows, thermal mass, and thermal chimneys are common elements found in Passive Solar Design. In fact, windows, walls, and floors are designed so they can collect, store, and distribute solar energy in the form of heat in winter and reject solar heat in summer.

Passive Solar Design

Passive Solar Design

Installing double or triple glazing, in addition to insulation throughout the building, can dramatically improve the internal temperature and relative humidity year-round. This all adds up to a huge saving on utility bills for the homeowner and, at the same time, greatly reduces the amount of reliance on energy consumption – helping the environment.

While Passive Solar Design can be more expensive to construct with the initial capital outlay, this cost is likely to be offset in the medium-term through its energy efficiencies and very low maintenance or running costs.

Passive Solar Design Principles for Tasmania

  • Directing sun into living areas. Position these rooms in the northern quadrant. At Natural Energy Designs, we aim to place kitchens/dining rooms and the living area/lounge in the north to east side of house, with bigger windows to the east and north. They are to have high operable (open and close) ventilation at the top of the windows, which allows for the expulsion of heat in mid-summer, while still capturing full sun in winter.
    This means the sun can come in early in the day and start warming up the home. As the sun rises to the midday heat it is then blocked by the eaves, before coming in again in the late afternoon.
    We aim to have minimal windows in the afternoon, (unless views are important in that direction), as that sun is still quite intense and tends to overheat the house with dry heat that makes it uncomfortable to sleep in (not to mention it fades the furniture etc.).
  • Angle of the sun.

    Directing sun.

    The angle of sun varies from summer to winter. Therefore, the sun is lower in winter (24 degrees) so will come further into the house, and higher in summer (71 degrees), so will be blocked out by the eaves.

  • Rooms that need cooling are placed in the south. We keep minimal windows in the south – due to heat loss – but some rooms you want cooler too.
  • Window types
    We don’t need to use double glazing, BUT… it is a no brainer to have. WHY? Because of the stability it provides with the air temperature. (Not to mention the added advantage of reducing sounds from outside).
    After living in a home with double glazing, you WILL notice the difference. The better the quality of glass used, the less heat that will escape. The optimal gap is between 12-16mm between the 2 layers of glass. By law, the glass must be more than 4mm thick. 6mm is ideal. The gap can be either vacuum air or argon gas. Argon gas is the best.
    With various combinations of glass thickness, (with or without a special ‘low-e’ film that assists in reducing the UV rays) and the gap sizes, we end up with various qualities of performance in the double glazing. This is quite a technical process that is best to talk with your window manufacture, to receive the ‘U’ values and ‘SHGC’- Solar Heat Gain Co-efficient values. (refer to for assistance here).
  • Thermal Break Frame.

    Then we have the frames
    Timber or PVC is the best, as they do not conduct temperature, (heat or cold) but they are costly. Then there are various aluminum types.  A Thermal Break Frame is a frame that has a substantial rubber insert that separates the outside portion of the aluminum from the inside portion of the frame. This means the cold air will not be able to pass through the aluminum, which is a very good conductor of the cold. A similar but cheaper product option is a thermally ‘improved’ frame that means the rubber break is a thin cheap strip, which is not ideal, but certainly helps. A solid aluminum frame is the cheapest option; however, there will be heat loss, so look for a thin frame. The less frame depth the better in this case.

  • thermal mass passive solar

    Thermal Mass.

    Thermal mass
    Good design has Thermal Mass. This is a structure that will hold the heat that is collected through the day and release it at night. It can be a concrete slab, with or without tiles. Rammed earth, straw bale, or a brick wall that is exposed to the sun through the day, or any other solid material that retains heat.

passive solar 21st december

Summer (Dec 21st) in Launceston.

passive solar 21st june

Winter (June 21st) in Launceston.

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2 replies
  1. michael
    michael says:

    Some really helpful information.
    I came here to help decide on roof pitch to accommodate solar panels. As I do not want ugly (panel) frames on my roof I wanted to incorporate this into the design.
    It appears northern Tasmania requires and roof pitch of around 47 degrees to make panels useful in winter and sadly I just can’t go this sort of pitch as the house would look ugly.
    Any input into how best to get around such a basic issue? Thanks


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