Have you ever been travelling in a cool climate and had that feeling in the dead of night that it might be colder inside your accommodation than the actual temperature outside? Or perhaps you’ve been sitting inside on a hot summer’s day, complaining about the oppressive heat, only to venture outside and discover it’s actually cooler out there? If these are familiar sentiments then it could be that the building you are in is lacking passive solar design – it’s about building green.
Passive solar may be an often overlooked feature of home designs in some areas around the globe but it can play a huge role in effectively regulating the temperature inside. What is passive solar design? Basically, it involves designing a building to make the best possible use of free resources (sun, wind, etc.) in order to maintain a comfortable internal temperature all year round. The goal of this is to reduce the use of powered heating and cooling systems, which will, in turn, save you money on your annual utilities.
For example, since Australia is covered by an extremely varied range of climate zones (there are eight in total) there is no “one size fits all” solution to passive solar design. An experienced architect in the local area will be able to tailor the design approach to make the most of your specific climate, but most will follow a range of tried and true principles for creating an effective passive solar design:
1. Correct Orientation
If you’ve ever heard builders, architects or real estate agents expounding on the benefits or a sun facing home in cooler climates, it all comes back to passive solar design. The importance of correctly orientating a home cannot be overstated; it should make the most of natural shade and sunlight, working on what will best suit the climate. For example, most architects will emphasise the importance of placing living areas and bedrooms to the sunny side of the home in cold climates, because this is where they will receive the most sun exposure during the cold season, but can be easily shaded in hotter months. Obviously, a different approach would be needed for a home being built in the hot climates, where architects would instead orientate the home to make the most of cooling breezes.
2. Benefit From Natural Heating
During the cold winter months, the sun doesn’t rise as high in the sky as it does during summer. This principle can be utilised to encourage natural heating because a home that has the main living areas on the northern face will receive more winter sun on these rooms. In turn, if these rooms contain a high number of north facing windows, then that winter sunlight can penetrate far into the home, creating natural warmth.
3. Take Advantage of Shading
During the height of summer, a home can become unbearably hot if the sun is beating directly down onto the windows. Since the sun is situated higher in summer, it can reach a greater number of windows, but this can be reduced by taking advantage of shading. With this in mind, consider the size of the eaves, as well as the placement of awnings or pergolas. A well-planned shading design will minimise sun in summer but still permit plenty of warmth when the sun is lower in winter. For this reason, it can be beneficial to engage an expert for planned home improvement projects, as they will be able to ascertain to what extent the proposed works will improve or diminish shading.
4. Plan Your Vegetation
In addition to receiving shade from awnings or pergolas, a good landscape design can be of benefit to an overall passive solar design. When creating a landscaping plan it is important to consider not only the location of vegetation but also what type will be planted. A popular approach is to focus on planting dense foliage along the western edge of the property, as this will work as a screen during the hottest part of the day (generally in the afternoons when the sun is setting). Additionally, planting deciduous trees will ensure the home is shaded in summer, but allow extra sunlight in during winter when the trees drop their leaves.
5. Don’t Skimp on Glazing
Whereas upgraded glazing used to be viewed as somewhat of an elite design choice, it is now viewed as a necessity. Studies have shown that glass windows account for as much as 87% of heat gain and over 40% of heat loss, a staggering figure when you consider how much this will affect your need to use mechanical heating or cooling. In addition to correct placement of windows, discuss with your architect or builder the various glazing systems available and go with the very best option that will suit your budget – you’ll make the money back in long-term energy savings!
6. Don’t Underestimate Natural Cooling
A cooling breeze can work wonders to reduce the interior temperature in summer, so it’s a good idea to maximise the natural air flow through your home. This generally involves having an entry point and then an exit point on the opposite side of the room – for example, bi-fold doors that are across the room from a bank of louvered windows. Installing ceiling fans will also help to make the most of natural cooling as they will boost air circulation throughout the home.
7. Understand Thermal Mass
Dense materials will naturally capture and store heat, an effect referred to as “thermal mass”. Common building materials such as concrete, brick, stone and rammed earth will all retain heat for longer periods than other items such as timber or steel. In climates that experience warm days but cooler nights, homes with thermal mass will store the daytime heat and keep the inside warmer throughout the cold night. A growing trend in these areas is to incorporate an exposed concrete slab and internal brick wall and then use an exterior cladding. This concept is known as reverse brick render and is considered to be very thermally efficient.
8. Maximise Insulation
Installing sufficient insulation is a proven method for keeping a home cooler in summer and warmer in winter. This is because it creates a barrier that keeps heat out on hot days but stops heat from escaping when it is cold outside. A new house with a timber frame can have added insulation placed in the wall cavities to boost this effect, whilst existing homes can retrofit ceiling, underfloor and even wall insulation to improve the passive solar design.
9. Use Weather Seals
Most homeowners are unaware that 20% of a home’s heat can be lost through the narrow gaps around windows and doors. By installing weather seals (any easy job even for an existing house) you can reduce the amount of heat that is lost, as well as minimising unpleasant drafts. For an even greater effect, you can also install pelmets above curtains, as these will act as an added physical barrier.
Whilst every building is unique, a well thought out passive solar design will take into consideration all of the above principles. By consulting with experts and taking the time to think ahead, you can ensure that your home has an optimal passive solar plan that will reduce the need to rely on powered heating or cooling systems; a great result for you, your wallet and the environment.