The 5 main elements of passive solar build design

While the science or physics behind it is relatively simple to understand, ‘passive solar’ build design is an intricate topic that we couldn’t possibly cover in one article. However, it’s worth discussing because by incorporating passive solar principles into your next home – even loosely – you’ll have a home that is not only beautiful but comfortable, cheaper to run, easy to live in and naturally energy-efficient.

While Merit Homes are experts in the art of luxury homes more so than the complicated elements of passive solar builds, to varying degrees, the principles are incorporated into every one of our homes. A standard of energy efficiency in all new homes is required by law, and it is undoubtedly an area of strong focus for us, our contractors and our clients too. It’s worth considering now because the most economical time to achieve good passive design in a home is in the initial planning, design and building stages.

Read on for a very brief explanation of each passive solar design element, and come back to see simple ways to incorporate them into your next home.

The light collector – ‘Aperture’

The light collector refers to large, sun-facing glassed (windowed) areas in your home at which sunlight can enter the building. In Australia, the ideal aspect for windows to face for optimum use of natural sunlight is to the north. 

Natural light streaming through your home is not only beautiful and a natural mood enhancer, but it serves two purposes for energy efficiency. Great use of natural lighting means you can use artificial lighting less, and sunlight also adds warmth, reducing the need for additional heating in winter. 

In Summer, the sun sits higher in the sky, so wide eaves help to reduce the amount of sunlight and heat entering the home.

The Heat Absorber

This is a hard, darkened surface, which could be a masonry wall, floor, or water container, that sits in the direct path of the sunlight and absorbs heat throughout the day, storing it in the ‘thermal mass’ behind. 

The Thermal mass

The thermal mass is the material that retains or stores the heat produced by sunlight. This could be a sun-facing brick wall or a concrete slab. The ‘absorber’ is the dark outer surface exposed to the sun, the thermal mass is the material beneath this surface that retains the sun’s energy (heat) that it will release into the home throughout the day.

The Distribution

This is the method by which the stored energy or heat collected in the thermal mass circulates throughout the house. This may include fans or ducts, or just the natural behaviour of the thermal material – a wall, for example – which radiates warmth collected throughout the day into the home overnight.

Control

Here’s where the design is controlled to suit the season. The sun hangs lower in winter, so although the climate is cooler, sunlight is able to penetrate through sun-facing windows well.  In summer, the sun sits higher in the sky, so the home’s eaves (roof overhang) shade the sun from the light collector and heat absorber, allowing less heat to penetrate inside. 

Another example of the control element is airflow and ventilation. Take advantage of the breeze by placing windows to capture and circulate the cool air throughout the home.  

Next up, we’ll discuss ways to use passive design principles in your next home.