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May 22, 2014 Comment

Has the Nest-led smart heating revolution overlooked the fundamental science of comfort?

In recent months we have seen a rapid increase in the development of smart heating solutions designed to anticipate and deliver our comfort needs, whilst minimising the energy required to do so. With so many options becoming available, it’s easy to overlook the fact that thermal comfort is extremely complicated.

The way we feel warmth is affected by a myriad of factors right down to details such as what we have eaten or drunk recently, and the average outdoor temperature over the previous seven days. And yet for the past 120 years we have relied on only one factor to maintain our comfort: air temperature. Unfortunately, air temperature is a factor that has little effect on our comfort. In short, we’re ploughing massive resources into developing highly sophisticated solutions to deliver smarter and smarter control of the wrong factor.

The problem comes down to our blind faith in the humble thermostat, a device that has changed very little from when it first emerged for domestic purposes in 1895. A thermostat is basically a feedback mechanism; it is designed to measure the air temperature where it is located and maintain that temperature constantly by switching the heating on and off. It cannot account for all the other influences that affect our comfort, or for what is happening in the rest of the house.

For example, the air temperature that the thermostat considers to be just right will be too warm if there is a radiant source of heat such as the sun shining through the window, and too cold if there is a draught. On a sunny day a home at 19ºC may feel warm, but as the sun goes down it may feel cool at 20ºC.

The warmth we feel comes predominantly from radiant energy; keeping that energy topped up is the best and most efficient way to remain comfortable. A thermostat does not provide the level of control that people desire or expect. In our rush to deliver smart home energy management services we have forgotten to stop and consider whether the fundamental heat delivery management device is actually fit for purpose.

All of which means that the rapidly developing new generation of smart thermostats are innovating around a flawed concept. New devices are being designed to automate heating programmes, learn your preferences and detect occupancy, but they can only deliver this functionality within the limited capabilities of the thermostat. There is nothing inherently wrong with smart, and the Nest-led revolution has made great strides in making energy efficiency and the timetabling of heat more desirable. But if we understand that the control device they are built on is not the best means of controlling comfort, then innovating around it seems like a waste of resources.

Perhaps more of our resources should be applied to reexamining the fundamentals behind our heating systems and exploring new approaches for how best to deliver and maintain a comfortable environment in the most efficient way. The momentum behind home control and automation is clear but if we are serious about the objectives of reducing consumption and saving money whilst maintaining comfort, we need to ensure it’s a revolution built on sound principles, not an evolution constrained by its reliance on the thermostat.

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