The main source of free energy comes from the sun, which generates electromagnetic radiation with varying wavelengths. This solar energy includes light, infrared rays (heat) and potentially harmful ultraviolet (UV) rays.
As well as low cost insulation, you can reduce a building’s overall long-term carbon emissions by using design features that maximise free solar energy. This is known as ‘free solar gain’.
Free solar gain
Capturing ‘free’ solar energy falling onto a building minimises the need to use fossil fuels for heating and lighting. Combining this with natural ventilation can also reduce the need for mechanical systems such as air conditioning.
Solar gain also has positive health and aesthetic benefits, and in the long-term can substantially reduce a building’s carbon emissions if designed to work in harmony with the principles of convection.
Passive solar design involves a range of features such as:
- double or triple-glazed south-facing windows - which allow infrared radiation to pass through - plus smaller north facing windows to minimise heat loss
- light tubes which channel sunlight from an outside roof or wall into a room during the day
- Trombe walls – natural design features which move warmer air into a space using convection principles
- a double-glazed conservatory or a solarium.
These and other design features can increase a building’s natural solar gain and minimise the need for energy sourced from fossil fuels or from renewable energy installations such as solar photovoltaics (Solar PV).
In hotter months, you can shade and ventilate glass conservatories to protect people and furnishings from excess heat and ultraviolet rays (which can cause skin cancer). If the same space is thermally isolating from the main building using insulated doors or windows, heat loss at night can be reduced.