passive solar techniques and the climate issue
Passive solar homes are designed to get their heating and cooling needs from the sun, wind, trees, or from the windows and the materials used on the walls and roof of the house and the way they interact with the environment and landscape. Passive solar plans intend to dispense with furnaces, boilers or air-conditioning...
Passive solar techniques
To reach their goal, passive solar techniques rely on the...
- thermal storage or reflectance of the materials used in their walls, floor and roof;
- building's sun exposure (which depends on its shape, axis, layout);
- natural ventilation (dependent on windows, windbreaks, orientation of the building);
- proper shape and orientation of the house;
- advanced windows, skylights and venting elements and overhangs;
- appropriate colors (of the walls and roof…) and specific elements as sunrooms, wing walls, trombe walls, water walls, roof ponds, diffusing glazing materials;
- other elements dependent on design, architecture and landscaping.
In other words, passive solar homes use a set of passive solar heating techniques and passive cooling techniques.
A strategy for new homes
Passive solar techniques are mainly a set of strategies to implement while you are projecting a new home. It's impossible to apply most of them on existing homes: we can't change the orientation and shape of a home, or the materials used in their walls.
The use of mechanical and active techniques
The aim of solar passive cooling and heating is to get a natural cooling and heating. But doesn't collide with the use of "active" techniques such as fans or solar water heating. They are indispensable in many cases. An example: fans are indispensable in hot humid climates, where you can’t fight humidity through natural ventilation or other passive principles…
Passive solar house plans and climate
Most of the passive solar designs are geared towards heating and cooling in cold and temperate and dry climates.
Obviously, there are some general principles applicable in any climate: properly sized overhangs, principles of thermal and storage mass and reflectance, shading through trees…
But some principles or measures are very specific to some climates. The shading of trees can't be used extensively in cool and cold climates. That strategy should be analyzed with extreme care, according to specific micro climes and climate conditions. On the other hand, in hot and humid climates we should use some particular techniques, that we do not use in cold climates:
- orientation of the house to avoid the direct impact of sun, instead of the opposite;
- extended use of verandas and shade nettings;
- intense use of mechanical devices to control humidity, etc.
Each climate determines the final passive solar techniques, and your plan should reflect it. Some of the techniques are universal, but others are specific to some microclimates and climates zones.