Paul Morris from Solar-Shield explains how external shading can help control solar gains and reduce internal temperatures, keeping your home cool as temperatures rise.
Interview with Paul Morris
Paul Morris is a third generation blind maker and external shading specialist at Solar-Shield: Exterior Shading Solutions. They aim to deliver a range of different shading solutions that not only help to keep your home cool during the summer months, but provide a more constant indoor temperature all year round. In this chat, Paul highlights the benefits of using external shading over internal blinds.
Internal blinds aren’t effective when it comes to temperature regulation
Paul begins by explaining the difference between internal and external shading methods and their ability to keep the heat out of your home. When the sun shines, it transmits short wave energy which as it passes through the glass in your window is absorbed by your furniture, floor or walls and is re-radiated as long wave energy. This long wave energy can’t pass back through the glass of your windows and as a result the heat is trapped within your home, creating a greenhouse effect.
By using internal blinds, you may feel as though you are blocking the sun and therefore keeping the heat out, but the heat is still being absorbed by your blind and radiating that heat back into your room. External shading methods aim to absorb this short wave energy before it has a chance to pass through your window and to radiate it back outside as long wave energy.
“So the simple thing is, stop the sun before it hits the glass and you solve the problem.”
External shading has been popular in other Northern European countries for many years
Paul debunks the common misconception that external shading is only for hot climates and explains that countries like Germany, The Netherlands and Scandinavia have been utilising the technology for many years because they understand the principles. The UK building industry lags behind, but as summers get hotter as a result of the climate crisis, more people are beginning to recognise the value of external shading.
External shading offers year long benefits
Temperature regulation and heat reduction are often seen as the primary benefit for installing external shading. However, Paul also highlights that they don’t just act as heat gain reducers. They can also insulate, provide privacy and let you control light levels.
“So some people will have external blinds on the north facing windows, so that during the winter they can keep some of the heat in. There’s more than one benefit in using external shading.”
Building regulations now address overheating
Paul explains that there are two main markets for external shading: retrofit and new build. The retrofit market is the biggest and is often driven by the problem of overheating – people are getting too hot in their homes and therefore seeking solutions. New build homes must comply with building regulations (Part O), which considers overheating and one solution included in the guidance is external shading.
External shading can come in many different forms
External shading is not a one size fits all approach and Paul recommends looking at all of the different options to see which will be best suited to your home. External shading can be grouped into two categories: dynamic and passive (or fixed). The dynamic shading methods are ones which you can move and control, allowing them to serve different functions at different times of the day or year.
Dynamic shading methods include external venetian blinds, awnings and roller blinds – which normally use a screen fabric with an open weave that allows a view through.
Fixed shading is part of good house design and may include roof overhangs and deep reveals around windows. For example the overhang at Hazel Tree House helps shades windows from the high summer sun but still allows the low sun in during the winter when solar gain in required.
Fixed shading can also be provided by pergolas, brise soleil or even a tree – features that are there all year round.
Include external shading in your design as early as possible
When approaching a new build or retrofit project, Paul recommends considering external shading as early as possible in the design process to ensure you have the most options.
Your architect or designer should have a good grasp on this, optimising the orientation of your home and thinking carefully about the shading. If you’re building to Passivhaus standard, this is baked into the processes but the Passivhaus Trust has some excellent guidance on how to design for summer comfort.
Whatever you decide, if you look at the options early the shading can be integrated much better into your building and there will be a seamless finish.
“When planning shading, plan it early, that gives you the most options. Very often we get called in quite late, and I say to people, it’s going to be a compromise. If you want to reduce the number of compromises you make on your design, speak to people like ourselves early.”
Dynamic shading can be radio controlled
Although dynamic shading solutions can be operated manually Paul suggests automated controls, particularly as this shading is external and may cover many windows.
If you’re hard wiring your blinds then the main consideration is power at first fix.
However, if you have an existing low energy home and you’re worried about drilling through walls and insulation then there is another option.
Some external shading products have solar Li-ion batteries which means there’s no need to wire them in. They can also be radio controlled from inside.
“If we were living in Northern Norway and it was dark for months of the year, you’d get about 60 operations before your battery started to run out. So in this country, realistically, with having daylight most of the time, the battery isn’t going to lose its charge.”
While exterior shading products can be used in conjunction with smart home technology, Paul prefers to use timers and set blinds on different windows to come into operation at different times. This method does require getting to know how the sun interacts with your building, but once you have worked out the schedule it is extremely effective.
External shading is resilient to windy conditions
A common concern surrounding external shading solutions is their ability to withstand strong winds. Paul explains that all external blinds have wind ratings and combined with a wind sensor, they can be resilient in windy conditions.
External venetian blinds are stable and will go up to 17 to 22 metres per second of wind before they need to be retracted. External roller blinds have a greater resilience, whilst awnings will need to be retracted at lower wind levels. Paul recommends having a wind sensor on all external products to automate these retractions and act as a fail safe.
“No matter where you live, whether you’re on the Western Isles of Scotland, down a valley with the wind whistling up it, at the top of a hill, they’re a lot more resilient to wind than people realise.”
MicroLouvre is the top choice when it comes to sustainability
Paul recommends MicroLouvre for those looking for a sustainable solution to external shading. MicroLouvre is a passive external screen that is manufactured from 80% recycled materials. It has a 60 year lifespan and is 100% recyclable at end of life. During its life, it uses no power whatsoever and is maintenance free.
Fitting your home with external shading might cost between £5,000-£10,000
The price of external shading solutions very much depends on the size and scale of your project. Paul explains that the average order for a new build is between £5,000 and £10,000 but can be more for larger projects. While there are benefits to having external shading for your whole house in practice there is a law of diminishing returns so prioritising the problem areas first is a good approach.
“If we’re talking about a large set of bifold doors, say, 5 metres wide by 2.2 metres high, you could be looking between £2,000 to £4,000 depending on the product used.”
Find out more
Visit the website of Solar-Shield: Exterior Shading Solutions
Go into more depth on integrating external shading into your designs in our training session in The Hub.
Transcript
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