Passive Solar Design
Explore our collection of Passive Solar Design
featured on Lunchbox Architect.
"In passive solar building design, windows, walls, and floors are made to collect, store, and distribute solar energy in the form of heat in the winter and reject solar heat in the summer. This is called passive solar design or climatic design because, unlike active solar heating systems, it doesn't involve the use of mechanical and electrical devices." -- Wikipedia
Would you believe a house using Passive Solar Design principles often doesn't need any additional heating or cooling? All it needs is free energy from the sun — not even fancy photovoltaic cells or complicated heat transfer systems.
Think of how much money and energy you would save if you didn't have to pay for heating and cooling — 40% in most cases (and much more in some climates).
That's extra cash you could be spending on fine dining and cocktails!
A Passive Solar House relies on six basic principles. If you get these principles right, you could eliminate your heating and cooling bills for good:
Climate
Passive Solar Design principles vary depending on your climate. In the tropics, using the sun to heat your homes would obviously be a bad move. Instead, cooling and ventilation is much more important. Whereas in Alpine areas, the house will probably never need cooling to maintain a comfortable indoor temperature. Temperate climates fall somewhere in the middle, usually requiring heating in the winter and cooling in the summer.
So, based on your climate, a Passive Solar Design will look and behave differently. In the tropics, large overhanging eaves shade the home from the sun and ventilation is essential to keep to space cool. While in cooler climates, eaves are sized to let the low winter sun in to warm up the home, while blocking out higher summer sun.
Orientation
Because Passive Solar Design relies on the movement of the sun, orienting your home correctly is essential. In Australia (and other countries in the Southern Hemisphere), the ideal location of windows for Winter heat gain is North, because the sun rises in the East and travels through the North sky before setting in the West.
In Europe, North America and other areas in the Northern Hemisphere, the opposite is true. The sun still rises in the East and sets in the West, but it travels through the Southern sky, so for maximum Winter sun, windows should face South.
Shading
Let's not forget shading. In the tropics shading is super important to keep the home cooler throughout the year. With the exception of the most frigid climates some level of shading is important in cooler climates as well to prevent overheating in Summer.
Because the sun is higher in Summer than in Winter, shading devices in temperate climates can be designed to block out the Summer sun, but still allow the Winter sun in.
Deciduous trees or creepers are another way to shade windows because they work in sync with the seasons. In Summer, lush green leaves will protect your home from the sun. In Winter the plant drops its leaves to let the sun shine in.
Thermal Mass
Have you ever stepped on or touched concrete after the sun has set to find it's still toasty warm? That's because concrete is great thermal mass — it absorbs and then holds heat for a long time. Materials with high thermal mass (like concrete, brick and even water) are like a thermal bank account. When times are good and the sun is shining they'll absorb the heat energy. Then, when that heat disappears (when it's cloudy or the sun has set) they'll slowly release that heat back into the atmosphere. When used in a home, this helps to moderate the temperature between the day and night.
The reverse is also true, if you cool down concrete or any other material high in thermal mass, it will stay cool for a long time, radiating that 'coolth' back into atmosphere.
When used correctly, thermal mass is a great way to store the sun's energy to keep the house warmer at night or when it clouds over. In summer (or tropical climates), the thermal mass can be used to keep the home cooler.
Ventilation
In many climates, cooling is just as important (if not more important) as heating. So how does Passive Solar Design cool a house? The sun itself isn't very good at cooling!
The key is ventilation.
Passive ventilation replaces hot, stale air with fresh, cooler air. Techniques like the stack effect achieve this replacement very efficiently. Depending on the site and climate, you might also be able to capture natural cool breezes, like evening sea breezes, for example.
Our bodies are pretty good at moderating our own thermal comfort. Perspiration, for example helps to keep us cool. But perspiration only works when the moisture can be evaporated off our skin — enter ventilation. A decent breeze can keep us feeling comfortable even in extremely hot conditions.
So ensuring the home has good ventilation — particularly cross ventilation — and encouraging the air to be drawn into the home from the cooler, shady side of the house will keep the house cool and comfortable even during the peak of summer.
Combine good ventilation with thermal mass and you can use the cooler night air to keep the house much cooler during the day.
Insulation
The final key principle of Passive Solar Design is insulation. Insulation in temperate and cooler climates is incredibly important. All our efforts to passively heat or cool the home will be lost if the home isn't well insulated from the outdoor temperatures.
The type and extent of insulation will vary depending on your climate. Tropical climates will require little to no insulation, while a very cold climate will need double or triple-glazed windows and very thick bulk insulation in the walls to keep the warm air inside.
It's particularly important in a Passive Solar Design to insulate the thermal mass from the outdoor extremes. This will help the thermal mass to moderate the temperature of your home day and night and season to season.
Thinking About Passive Solar Design
A good architect will consider Passive Solar Design as a matter of course. Passive Solar Design isn't a fancy additional extra. For the most part it doesn't cost any more — in fact over the life of your building it can save serious money. It's easy to achieve with new buildings and improvements can often be made even in poorly designed existing buildings.
There's really nothing better than basking in warm, natural sunlight in your comfortable, efficient home when it's freezing cold out, or opening up your house to cooling natural breezes on a warm Summer's night. Passive Solar Designed homes are more comfortable year round, cheaper to run, and much friendlier to the environment.
Check out some of the projects using Passive Solar Design featured on Lunchbox Architect:
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Carpenter’s vision meets architectural brilliance: transforming a dark, outdated house into a light-filled, energy-efficient family home.
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Who would have thought a modest red brick project home could be hiding so much potential. The transformation is stunning...
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Responding to its unique landscape and climate, this home is the kind we should be building in Australia, not more McMansions.
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Clad in native timber, Silvertop House is at home in the country or the 'burbs and you can purchase the plans to build it on your block!
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Taking advantage of a mature native landscape, this home captures all the right views so it feels like you're floating in the treetops.
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Bungalows are charming homes, but they tend to be dark. This addition finds a way to bring light into the depths of this bungalow.
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The front verandah of this Californian Bungalow is reinterpreted at the rear of the home to create a shady outdoor living space.
Designed with sustainability, low maintenance and natural ventilation in mind, this is a low-budget family home with a difference...
Access to natural light is so important, yet often overlooked. With thoughtful design, your home can be light and bright year-round.
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Passive solar principles, high-quality yet affordable materials and thoughtful design brings high-quality housing within reach.
Bringing together all the things they loved from previous houses, their new home represents the good life for this family of five.
This new home in a semi-rural estate balances a sense of space with a need for privacy so the shift from the farm life isn't so hard.
While older homes have character baked in, they're not built for modern living. But, you can have the best of both worlds; old and new!
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For tree-changers Matt and Leanne, an important part of their ideal home was making the most of their spectacular site.
This family home was designed with best-practice sustainability and Passive House standards to be a comfortable home for years to come.
A modern farmhouse for a couple with overseas relatives needs to adapt from a comfortable home for two to a home for many more.
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The neighbours are shifting uncomfortably in their seats as this new kid on the block shows them what modern living should look like...
The practicality of a classic hat proves the perfect design inspiration for an off-grid home in Australia's outback.
Would you be game to renovate and reduce the size of your home? This design proves it's not always more space you need, after all.
Using passive design techniques, this new living space embraces the outdoors and will be comfortable year-round without relying on AC.
Sitting on an exposed hilltop, this off-grid retreat deals with a hostile landscape, but it's worth the effort for that view...
When you think of an off-grid house you typically imagine a remote cabin in the bush, but these eco-townhouses tell a different story.
A private, yet light-filled coastal home is the perfect fit for a retired couple, with plenty of room for visitors.
A new opening with integrated seating transforms this home from dated colonial-style, to modern, minimal and cool. What a difference!
Oriented for passive heating and cooling and taking in stunning views of the landscape, Paddock House feels right at home in the bush.
Celebrating an incredible rural site, this eco-friendly home opens up to the views, basks in the sun and collects all its own water.
Living in the inner-city means trading space for convenience. This project shows you, that trade-off isn't so bad.
If your backyard doesn't face north, create a long side yard instead so you can enjoy the benefits of natural light and passive design.
With an incredible site just one street from the beach and close to the city, these architects built their ideal family home.
A modern beach house design replaces the ageing cottage on a property that has been in the family for over 50 years.
Like an annexe attached to the side of this solid home, BENT Annexe is an open-plan living area that feels more like a garden room.
A relatively modest-sized home feels more spacious and comfortable thanks to its connection to and interaction with five garden spaces.
By designing a new, open-plan addition to this heritage home, the owner has a light-filled space to inspire his creativity.
Buying an extra slice of land from the owners' corporation enabled this 1960s one-bedroom unit to become a modern three-bedroom home.
The good qualities of both old and new are highlighted by creating an addition which is the binary opposite of the original.
Sub-tropical climates require a special approach to design to ensure they are comfortable in the sticky summers and the cool winters.
When the inhabitants of your suburban fringe block include a number of old native trees, mimic their style and go timber all over.
This warm, textural home creates a connection to place, captures views and creates a humble retreat from the elements (and the city).
This house had become a squat and burnt down during the design stage, but Dean and Lisa transformed it into a modern, sustainable home.
On a long, narrow site, a courtyard is cleverly cut into this addition to allow the sun to stream into new living spaces.
A decked courtyard connects this existing home and extension, providing light, breezes and an indoor-outdoor connection to old and new.
It's surprising how many everyday items can't be recycled. Being fully recyclable, this home is surprising for the opposite reason!
Living at home while your extension is built sounds like a nightmare, but this clever idea allowed the owners to live disruption-free.
This modern home captures the spirit of mid-century design, with a taste of American diner-style breakfast booths for good measure.
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With a passion for sustainability, these owners salvaged whatever they could to reduce the carbon footprint of their renovation.
Some tips to help you survive winter for when you're designing your new home or renovation. Because SAD is not becoming on anyone.
With open-plan living and shared sleeping areas all opening onto the outdoors, this is a home to connect with nature and each other.
A typical Australian home uses the full width of the block and puts a garden in front and out the back; this home is far from typical.
Even if you're stuck with a south-facing backyard overshadowed by your own house, there's no need to dwell in darkness.
Blessed with a large block in a good area, this family decided to downsize in the backyard, in spite of the constraints.
Craving more space (and sun) and considering a move? Are you really better off uprooting your family and moving somewhere new?
Clever thinking achieves a simple timber beach house the client desired while still meeting bushfire and energy efficiency regulations.
Sitting sympathetically in an open paddock, this off-grid house captures views without compromising on environmental performance.
By dividing a complicated inner-city block into a patchwork, a new home sits comfortably between heritage buildings and gritty laneway.
It's Playtime in this fun-filled extension with secret hatches, a bridge, sloped walls and an aquarium of curious creatures.
