Building Layout & Design:
Passive Solar Design: Principles

Passive systems use the fabric of the building itself to collect, store and distribute heat. The design is influenced by the local climate.

The following are features of passive design:

1. house orientation,

2. thermal mass,

3. ventilation,

4. insulation,

5. emissivity,

6. window and awnings size and orientation,

7. natural lighting,

8. strategies to accommodate the local climate and environment, and

9. material selection according to thermal mass, insulation and emissivity, to provide maximum thermal benefits.

The Newton House passive solar design features have considered the heating and cooling requirements for the local climate.

Passive solar heating:

1. The house is orientated to the north to take advantage of the winter sun. The length of the house runs east west.

2. Thermal Mass - earth rendered walls, along with a stone feature on the floor in the bedroom, will store winter sun during the day, and give it back as the temperature drops.

3. Bulk Insulation - will slow the movement of heat out of the house in winter and into the house in summer. Straw bales have a mean R-value of 5.6. (This R-value has been correlated from available research data. Straw has been documented to have values far higher then this. Straw bales, however, are not a consistent variable, and render will further add to the final value.)

4. Window and awning size and orientation. The awnings are designed to give internal access for the north winter sun.

Passive Solar Cooling:

1. Ventilation - is enhanced through unobstructed cross ventilation from the south to the north of the house. Clerestory windows in both pods permit escape of heat that accumulates in a cathedral ceiling.

2. Reflective insulation - Air-Cell installed under the roof and under the floor has 97% reflectivity. The corrugated iron roofing will be white which has a further 79% reflectivity.

3. Window size, awning width and orientation. The awnings are designed to protect the interior of the house from the summer sun. No windows to the east and west prevents the low angle sun entering the house.

Newton House Building Envelope

A wall impedes, but does not stop, the flow of energy between two environments. The term 'building envelope' implies that all exterior surfaces are considered as one skin when combating external air temperature. Material characteristics of this envelope will affect the outcome. Insulation can be added to the envelope or wrapped around the envelope, but doors and windows will always be a source of air and heat leaks. Detailing of these areas is essential to prevent unwanted movement of air to weakening the whole envelope.

The preceding sections have reviewed the effect that local climate, desirable comfort, insulation, emissivity, thermal mass, orientation of house, ventilation and windows on the internal environment of a house. This section will summarise how the building envelope in the Newton House will function.

Area	Design Decision	Benefit
Roof	Corrugated iron, white colour lined with Air-Cell reflective insulation.	Highly reflective. Will reflect ~97% of heat away from the house.
Walls	Rendered Strawbale	High insulating R-value of straw. High Thermal mass in earth render.
Windows	Recycled single pane windows with timber frames.	Windows are recycled.
Window coverings	Well-fitted curtains with a pelmet. The occupants to minimise heat loss in winter will adjust these.	These will stop air movement over the glass surface, and loss of heat.
Floor	Recycled timber floorboards lined with Air-Cell reflective foil. Earth floor thermal mass. Dull dark colour.	Floorboards provide poor thermal mass benefit. This is improved by reflective foil under the floorboards that reduces the rate of air movement through the floor boards.   Earth has a high thermal mass. Situated to collect the north sun in winter will provide excellent storage and provision of heat for winter.
Internal Doors	Recycled timber doors.	Internal doors allow living area to be isolated, and control cross ventilation. This permits more control of the comfort of the house by the occupier.
Ventilation	Clerestory windows.	Will allow stacked heat in the cathedral ceiling to escape.

Architect: Anthony Donovan Architect
Structural Engineers:Mills Engineers

Links

http://www.air-cell.com.au
http://www.goldcoast.qld.gov.au/t_std2.asp?PID=388
http://renewable.greenhouse.gov.au/home/passive_solar.html
http://www.env.qld.gov.au/cgi-bin/w3-msql/sustainable_energy/msqlwelcome.html?page=index.htm
http://fridge.arch.uwa.edu.au/topics/thermal/solar/index.html