Principles of passive building design.

Searching the internet you sometimes come across little gems which one suspects are not actually meant to be in a public directory of the website.

Recently I came across an excellent article about passive design principles for housing. The article is in draft form so I am hesitant to publish the URL.

I will tell you that article is in MS word format and the the first line is "Passive design for ClimateSmart Housing" so you can search for it yourself.

The article's focus is on housing in the state of Queensland Australia, a massive state which forms the north-east corner of the Australian continent and has a total area of 1.8 million square kilometres (or 700,000 square miles).

Queensland is 2 and ½ times the size of Texas in the USA and is 4 and ½ times the size of Japan so the state covers a range of climate zones.

Where The Woman and I will live, the climate zone is Sub-Tropical, coastal.

Irrespective of where you live or build, these six principles are valid, although they way the are applied will of course differ depending on the climate in your area.

We know that to build a house that is comfortable to be in and energy efficient, we need to incorporate six passive design principles which, according to the article, in order of priority are:

1. "orientation – generally, wherever possible, orientate the living area to the north for winter warmth in the cooler parts of Queensland and away from the summer sun in north Queensland. Utility areas such as the garage, storage rooms, entry and laundry should be positioned to the south-west to shield the house from the setting sun.*

2. ventilation – openings throughout the house allow summer breezes to provide cooling cross-ventilation.

3. shading – effectively shading walls and windows prevents heat transfer e.g. roof and window eaves.

4. insulation – insulate the roof space against heat and cold transfer, and insulate the walls where no overhangs are provided.

5. thermal mass – build in thermal mass to absorb heat where it can be useful to re-radiate this heat at night (NB. this principle applies mostly to Zones 3 – Hot Arid, and 5 – Warm Temperate where hot days can be followed by cool nights).

6. materials – use energy-efficient materials appropriate for the climate zone to improve thermal performance e.g. external walls, windows/glass/tinting and solar pergolas. "



Note: To point 6 I would have to add colour. Light coloured finishes to walls and roofs can reflect a lot of heat.
The space between your ceiling and roof can get very hot so do what you can to reduce that heat. Insulate of course but avoid dark colours on walls and roofing.

Solar reflective paint is now being advertised with claims that it reflects the sun's rays.

In Australia the versatile steel products such as Colorbond steel is increasingly popular as a roofing material, so much so that it is trendy and is now therefore manufactured in a wide range of trendy colours, light dark and in-between.

Putting a black steel roof on a house in a sub-tropical location would seem very silly.
But I could show you where it has been done. Difficult to believe that the builder and the roofer would not advise strongly against this.
But then the customer is always right, right?

*Orientation given is for the southern hemisphere. North of the equator you would- orientate the living area to the south.

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