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Passive Solar

The Basics

Much of the material within this web site by Emilis Prelgauskas architect presupposes that the reader has some prior understanding of energy efficiency and environmental matters.

This approach was satisfactory when this web site first began, and while it was predominantly a specialist site on the subject.

Webmaster records show that increasingly, this site is being browsed for general interest. To assist those only just beginning in these subjects, this file below is added here as a quick 'primer' on the basics of building energy efficiency and ecologically sustainable development.

This background provides a framework which is relevant to the detail contained within this site's 4mb space and its 80 plus files.

An US commentator recently crystallised this practice's work as 'integrated functionality'; picking up on the emphasis visible in all of this practice's projects in making the many aspects of a building both work, and work well; rather than emphasising an aesthetic.

Broad planning for energy efficiency

Note: throughout this site the Australian desert context is assumed. North is sunward, south is downsun. For readers in the northern hemisphere, or other climate zones, appropriate adjustments should be made.

Building energy efficiency is a function of:-
1. - the passive capacity of the building to achieve comfort and habitability without relying on energy input.

This means daytime lighting should be 100% from sunlight (direct and indirect) even in overcast conditions. This requires large windows, and rooms with windows on several sides, and large rooms with windows in the centre ceiling above - see the 'clerestorey' section of this web site

2. - the building's long wall facing north toward the sun means getting enough (or shielding out excess) solar heat

In cold climates face the windows toward the sun, in hot desert climates face the windows away from the sun.

3. - insulate the perimeter shell (wall, roof, floor) of the building to stop excess heat in and outward movement. - see the 'ESD materials' section of this web site

4. - internally have heavy mass (rammed earth, mud brick, stone, clay brick) to absorb and retain heat from the inner air.

Together these approaches form the basis of 'passive solar' building design.
In Australia this is promoted by schemes like '5 Star Rating', "GMI" (glass, mass, insulation), and are incorporated in computer programs for energy rating schemes (NatHERS, FirstRate, etc.).

By these combined means the building passively moderates day and night hot and cold extremes, and maintains comfort internally generally without supplementary heating or cooling.


In desert ambient weather conditions additional cooling is required, and so shading, cross ventilation and adding moisture
(see the 'subsidence tower' section of this web site) add more passive or low energy systems to the architect's armoury.

This leads into the 'climate response' design approach fully described throughout this web site.

And there are even many more component pieces in achieving energy efficiency and environmental systems in buildings.

Further matters

Success depends on getting the detail right.

Energy efficiency depends on use of low energy appliances (ceiling fans, etc.) for cooling, and high calorific value fuel (wood or gas) for warming. And these facilities need to be integrated together with the building layout to achieve maximum effectiveness.

Ceiling fans don't work well when placed in the centre of the room.
And high energy input systems (geothermal, reverse cycle, etc.) should not ever be needed in a well planned passive building.

There is a role for the architect to teach building owners to use the building efficiently (this is called 'demand management', or 'weatherisation' in the US).

- see separate file on this web site.


The result of integrating all these matters into the building design are buildings which use 1/4 to 1/5th of the energy of conventional buildings.

At that point renewable energy supply systems become cost effective, and ecological sustainable development becomes practical.

The architect's knowledge extends well beyond the overview given here, and the details on this web site. That detail knowledge and past practical application, is what the client draws on by employing the architect.

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