External Blinds – A discussion with Guthrie Douglas
On 21st March 2023, the European Solar Shading Organisation (ES-SO) launched Global Shading Day, aiming to highlight the importance of solar shading when it comes to combating climate change and making our buildings more “climate resilient.”
This hugely important day aligns with our belief that solar shading will play a significant role in the design of sustainable and energy efficient buildings, through the use of automated shading, high performance fabrics and external blinds.
And with the second Global Shading Day fast approaching, we sat down with Guthrie Douglas’ UK and Eire Project Consultant, Mary Halpenny, and our A&D Manager, Dan Voller, to discuss the important role external blinds, in particular, will have.
Why do you think the UK is further behind the rest of Europe when it comes to using external shading systems?
MH:
I feel that the typical weather conditions in the UK may have led to a lesser emphasis on external shading compared to regions with warmer climates such as Europe.
Although, I have read recently that the UK’s Met Office have stated that summers are likely to become hotter due to climate change. Coupled with the implementation of PART O in 2021, which calls for external shading for residential buildings to reduce heat gain, we are seeing more focus on external shading for residential buildings.
My colleague who performs a similar role to me throughout Europe, sees a much higher demand for external shading on buildings, as it is more widely used and understood which takes away the fear of the unknown that exists within the UK market.
DV:
It certainly feels like the UK is playing a bit of ‘catch-up’ with parts of Europe in terms of demand and regulation for external blinds. Buildings in places such as Germany, Switzerland and France for example have, for some time now, made use of external shades and the legislation has been in place to facilitate.
I do see Part O as the first step in a greater call to action for the construction industry in the UK to consider how best to regulate internal temperatures, and external shades can be a great option to consider.
Do you believe external blinds will become an important part of designing sustainable buildings moving forwards?
DV:
Yes. One of the primary reasons we use blinds in our buildings is to prevent excess heat entering and becoming trapped, causing overheating. Ultimately, the overheating problem leads to increased reliance on mechanical cooling systems, which have their associated energy requirements and carbon footprint. External blinds are one of the most efficient ways to prevent excess overheating.
External blinds can reflect radiation away from the building without allowing it in through the glazing first, as would happen with an internal blind. There is a calculable energy saving to be made through active use of external shades, and this must be considered when we are designing buildings to minimise energy use and operational carbon emissions.
MH:
I strongly believe that dynamic external shading will play a prominent role in the facade design of sustainable buildings. We have seen firsthand the benefits of using external shading in the facade design and the impact it can have. One notable project is, One Sydney Harbour, whereby using a bespoke designed reflective fabric allowed the use of low-iron glass while limiting solar heat gain.
As advocates of the benefits of external shading, Guthrie Douglas played a key role in a steering group that launched the ‘Shading for Housing’ design guide in 2023, collaborating with industry experts and stakeholders from across the sectors. We were delighted to be part of a guide to help embed a new culture in which shading is central to the buildings design and built-in from the start.
Do the Part O regulations need to be updated to include commercial buildings, alongside residential, for external blinds to become more regularly specified in the UK?
MH:
We are seeing an interest in external shading on commercial buildings from certain architectural practices who seem to understand the huge benefits. However, with financial constraints often dictating the building design, they can be omitted from schemes. But this often ignores the long term cost saving on cooling.
If the Government were to prioritise sustainability with regulations, I believe that the industry would learn quickly and adopt, in much the same way as when Part L was introduced.
DV:
It would make sense to have a more consistent approach across building use types for Part O. I think it’s great that Part O offers strong guidance for our residential stock, and I’d like to see it expanded into the commercial space, as it would put a real drive behind ensuring our building design is fit for the (warming!) future.
External blinds and regulations
MH:
We need to ensure external shading systems are meeting the correct standards that have been set out specifically for our industry. The main standard is EN13561, which sets out the requirements for the operation of the systems in climate conditions, specifically wind resistance.
Also, external shading systems as regulated under the Construction Related Products with mandatory CE marking. See the below chart for clarification.
DV:
Agreed with Mary, we must make sure that we are specifying and installing compliant systems to current regulations. Fire regs have been a key talking point in the wake of events such as the Grenfell Tower disaster.
For external shades on relevant buildings, we currently must ensure that we achieve A1 or A2 s1-d0 fire classification on the part of the system that does the shading. Think the roller blind fabric or slat of a venetian.
The required classification does vary slightly depending on building use and height, so please do get in touch to discuss a particular scheme.
Conclusion
All Guthrie Douglas external systems are CE Marked with a defined wind classification. Through our partnership with Guthrie Douglas, we have access to all our test data in-house and, in the past, Guthrie Douglas, have conducted project specific wind tunnel testing if required.
Additional reading can be found on our website here or via the link to the Guthrie Douglas website.