Sunlight is bad.
When it comes to health and wellbeing, we are constantly bombarded with conflicting messages. Whether it’s protein, statins or red wine, they are alternately the hero or the villain of various scientific studies.
Sunlight suffers the same fate. We are encouraged to get exposure to the sun for vitamin D and for healthy circadian rhythms; but we must also cover up due to skin cancer risks.
Likewise for buildings. We harvest the free energy for daylighting, and to generate electricity and heat via solar panels; but we grapple with overheating and with glare from the same source.
So how do we manage this dichotomy? How can we maximise the good whilst minimising the bad?
Firstly we must acknowledge that this is a dynamic challenge. The sun tracks across the sky from sunrise to sunset, and its track is different for every day of the year. At least this is fully predictable variance.
The weather is another big variable, predictable only in the short term. A third set of variables is with the building itself: latitude, orientation and usage of spaces all play a part.
All these factors combine to produce enormous variations in the levels of natural light experienced by building occupants. Buildings designed to maximise daylight will likely have glare and overheating issues; those designed to block glare will end up being deprived of daylight on dull days and make excessive use of artificial lighting.
Clearly no static solution is capable of providing a satisfactory outcome. At best, it will only be effective for some of the time. At other times it will be detrimental to the building occupants’ experience and wellbeing. It will also increase the building’s energy consumption, either for cooling or for artificial lighting.
A dynamic challenge requires a dynamic solution.
Dynamic shading is required to make the most of the sun’s free energy whilst managing the adverse effects. A dynamic shading solution allows us to confidently design for daylight harvesting, knowing that glare and overheating can be managed in very bright conditions, but without compromising the daylighting in less bright conditions.
So what constitutes dynamic shading? At the most basic level, any form of shading that can be adjusted depending on the conditions could be called dynamic, as opposed to static. However, a truly dynamic system is one which can respond autonomously to the conditions.
We have long taken it for granted that thermostats automatically regulate heating and cooling systems. Increasingly, artificial lighting is controlled by occupancy and/or lux level sensors. Yet blinds are generally still left to be controlled manually, relying on human presence and inclination to maintain optimum conditions.
This often leads to the original design intentions and calculations for daylighting, overheating and energy consumption being compromised.
A successful dynamic shading system consists of two key components: the shading material and the method of control. If either of these should be prioritised it is the controls, because the very best shading material will not do its job well if not deployed intelligently.
It is essential that this is considered as early as possible in a project design phase, so that the optimum solution is designed in from the start.
Automated dynamic sun shading systems, using the latest shading materials and intelligent control technology, are the way in which we can harness the benefits of daylight without the harmful effects of glare and overheating. Bring on the sunshine!
This article first appeared in the Daylighting Magazine: https://issuu.com/bb2b/docs/daylighting_16/16