Giant windows. © McAteer Photograph by Alan McAteer

+ Engineers should design for less air conditioning and providing the end user with more control – convincing the client is the key to this strategy

I think that the majority of engineers believe that we often implement too much conditioning in the spaces we design. So what’s stopping us from designing for less conditioning and providing the end user with more control?

Michael Stych and Becci Taylor have both written Thoughts recently on the merits of openable windows in heating, ventilation and air-conditioning (HVAC) strategies, and the benefits of a variable environment on personal wellbeing. Thoughts that I agree with.

I believe that, where appropriate, we should design our buildings with flexibility in mind and accept that through the seasons the environment in which we operate will vary. This doesn’t mean the death of the fan coil unit or the full adoption of natural ventilation, but it does mean a more pragmatic approach to design than is perhaps the norm. 

The major obstacle that I see in achieving this is warranty. Warranty and trust. With a mechanically ventilated system it’s relatively straightforward to guarantee internal conditions. We are able to calculate loads, implement passive measures and size systems to meet demand. 

The risk is clearly held by us, the designer, the suppliers of the various bits of kit we incorporate, and those responsible for it all being installed correctly. It's easy to diagnose any points of failure and everything is bolted together in a way that ensures that most problems can be fixed with relative ease. 

In a system where environmental control is placed much more firmly in the hand of the occupant, the boundaries that define comfort and whether a system is working correctly are blurred. Keeping everyone happy (or telling them that they should be satisfied) becomes more problematic and more open to individual perception. 

Ensuring that an occupant has all the tools that they need to manage their environment, and (just as importantly) that they can intuitively understand those tools, is challenging. It means re-educating those in control - typically the owner or developer - about what constitutes a pleasurable and acceptable environment, and that this doesn’t mean sacrificing the comfort of the end user.

The challenge is selling this to our clients. We need to be great communicators. We should also assume that the end user is intelligent enough to grasp the basic concept of a variable environment.

A key element of designing for variable environments is finding several service strategies that can be amalgamated across the year. We shouldn’t be specifying systems that can cover 80% of the year but are only in use for the 10% that we actually need them. We should design them for that 10%. There’s no need to double up if we have confidence in what we’ve developed. It’s a hard sell to the clients and various other stakeholders, but it’s the right sell to make for various reasons.

I’m unsure of how we as engineers do this. What can we be doing to convince others that variable environments are appropriate in many of our projects?