What is passive solar and what can it do for you?

If you’re planning a new office space or other business premises, or indeed planning a retrofit of an existing building, getting the most bang for your buck will be a priority.

Good design can cut operating costs, improve productivity and wellbeing and even provide other benefits such as reduced environmental impact and extra PR value.

This article is about a particular design principle called passive solar. So, what is it, how does it work and how can it benefit you?

What it is

When hearing the word ‘solar’, most people think of solar panels. But that’s not the only way to harness the sun’s energy. Passive solar is simply optimising the sun’s natural light and warmth through low-tech design features such as large south-facing windows and good insulation. Making the best use of this passive solar energy is an affordable, sustainable and pleasant way to light and heat a building.

How it works

The three key ingredients to passive solar design are orientation, heat-retention and air-flow.

Passive SolarThe best orientation is south-facing, or within 30 degrees of south-facing. Large, often floor-to-ceiling, double-glazed windows bring in as much sunlight as possible and warms the inside via the greenhouse effect. Shades or louvres at the top of the windows can be used to prevent   overheating. They block out the high summer sun while allowing the lower morning and winter sun to warm the building. A west-facing orientation is prone to overheating because the late afternoon sun is too low to be blocked with louvres. An east-facing or north-facing orientation on the other hand is likely to be cold. If possible, arrange the layout so the offices and conference rooms (or shop-floor, studio or any other public or working spaces) are towards the south where they’ll benefit from sunlight, and place the hallways, storerooms and bathrooms on the opposite side.

Once the sunlight is brought into the building and trapped as heat, it needs to be retained. Double-glazing helps to do this, but insulation is the most important feature. Insulation acts like a blanket around the building, minimising heat-loss and also spreading heat more evenly around the building. Unlike a blanket, it can also reduce overheating in the summer because it regulates temperature rather than maximising it. You can get wall insulation and roof insulation. The costs and savings will vary widely depending on the building, but you could cut your heating bill by as much as 30% with proper insulation. Thick walls also add ‘thermal mass’ – helping to absorb heat when it’s sunny and slowly release it at night.

To make the most of passive solar you also need to control air-flow and make sure the building is very air-tight, so heat isn’t lost through tiny gaps around windows, doors and other openings. However, once you get twice as air-tight as the building regulations demand, you run into another problem, in the form of ventilation. If your building is super air-tight then just opening a window now and again will not be enough to guarantee healthy ventilation. You can get around this by installing a low-energy extractor fan, which chucks out stale air and allows fresh air in through vents. If you are planning a retrofit rather than a new-build, you can improve heat-retention quite cheaply with draught-proofing around doors and windows.

How it can benefit you

There are a range of benefits to using passive solar for offices and other commercial buildings. These can roughly be divided into economic, environmental and aesthetic benefits.

Passive SolarEconomic
Passive solar design significantly reduces energy bills. The actual reduction depends on many factors such as the size and location of the building and the behaviour of the occupants. To get a picture of what’s possible, a building that uses top-of-the-range passivhaus standards needs just a third of the energy used by a conventional building. Most people don’t achieve the pure passivhaus standard, but still make big savings. As mentioned earlier, insulation alone can cut bills by 30%.

As well as cutting your bills, utilising passive solar in your premises could also provide PR value. Consumers are increasingly concerned about climate change so showcasing your commitment to sustainability could set you apart from your competitors.

Finally, there are studies showing worker productivity is boosted by work environments rich in natural light and fresh air – both of which can easily be provided with passive solar.

In the UK, energy used in buildings accounts for 43% of carbon emissions, and the majority of energy is used for space heating. This means using the sun for heating and lighting can have a dramatic effect on carbon emissions.

Successfully tackling climate change will require all sections of society – including the business sector – to do their bit. To find out how much carbon you could save by using passive solar design, start by finding out the carbon intensity of your energy. That means the amount of carbon dioxide and other greenhouse gases that are emitted per unit of energy, usually kilowatt hours. Then, armed with this knowledge and your energy bills, talk to one of the experts linked at the end of this article.

Passive SolarFinally, buildings designed or retrofitted with passive solar principles are just nicer to work in. They are flooded with natural light, the large windows and open-plan layouts add a spacious expansive feel, they stay warmer in winter and cooler in summer and they benefit from natural ventilation with fresh air.

As well as adding commercial value to your property, this will also have a beneficial effect on the wellbeing of your staff and visitors, and ultimately reflect positively on your company.

Learn More

There are so many variables when it comes to using passive solar and other green building techniques, that it’s not possible to give accurate estimations on cost and carbon savings that will be applicable to everyone.

If this article sparked your interest, use these links to find out more:



Tegan Sonvico Christov enjoys blogging about sustainability and works as a Communications Intern for Koru Architects, a Sussex-based architecture practice specialising in eco-design and sustainable building. Working on residential and commercial projects throughout the South-East, Koru Architects has built a reputation for sensitive contemporary designs that fit comfortably within their surroundings and make creative use of light and space. Learn more at www.koruarchitects.co.uk or find them on Twitter, LinkedIn or Facebook.