Central heating systems have interfaces, and many of us interact with them every day, even if only by experiencing their effects.

But there’s a lot of room for improvement. They’re systems where (unlike, say, a car) we don’t generally get instantaneous feedback on the changes we make to settings or the interactions we have with the interface. It’s a slow feedback loop. We don’t necessarily have correct mental models of how they work, yet the systems cost us (a lot of) money. How effectively do we use them? Around 60% of UK domestic energy use goes on space heating, and 24% on water heating. (See this Building Research Establishment report [PDF] for more detailed breakdowns.) That 84% cost me and my girlfriend £430 last year. It’s worth thinking about from a financial point of view, regardless of the environmental aspects.

Frankie Roberto and colleagues at Rattle Research have carried out a brilliant exercise in exploratory design thinking about central heating*:

Heating systems are something we all interact with, especially in the depths of winter where we depend on them, and yet there seems to have been very little evolution in the design of their interfaces. What’s more, with an ever increasing focus on energy efficiency, both from an environmental and economic standpoint, there’s a need for heating systems and their interfaces to be smarter, more efficient and transparent.

Design Monday #1 – Central Heating (short version) from Rattle on Vimeo.

Read the full post.

The Rattle team think through existing systems and consider a number of possible revisions to improve the way that information is presented to users, and the level of control that it might be useful for users to have. This is a great piece of work, impressive and very thorough, and it’s interesting to see how their thinking evolved: I get the impression that (as service designers) they’re a lot more focused on users’ needs than the designers of many heating systems are. It’s also an exciting thing for a design company to be able to take time to address problems outside their immediate sphere, since they’re bringing a whole new level of domain expertise to it.

The ‘I’m working’ indicator is a really good idea – it reminds me of some higher-end car tyre air pumps at petrol stations where you can just set the pressure you want to achieve, and the pump cuts out (and alerts you) when it reaches it. But the idea of doing away with the ‘desired temperature’ setting and just having warmer/colder is also interesting – “forc[ing] people to always make decisions based upon how they’re feeling right now”.

Equally the ‘shift to service’ approach of having an API and making clever use of it has a big potential to help in energy saving (and cost saving for the user), especially if the usage data were (anonymised or otherwise) available for analysis. Just being able to tell users “it’s costing you £X more to heat your home than it does for a similar family in a similar house down the road – if you insulated better you could save £X every month” would be an interesting mechanism for persuasion. As with so many things, it relies on having that API or other interface available in the first place…

Folk theory of thermostats

The ‘folk theory of thermostats’ which Frankie mentions, popularised in Don Norman’s The Psychology / Design of Everday Things, has long intrigued me:

There are two commonly held folk theories about thermostats: the timer theory and the valve theory. The timer theory proposes that the thermostat simply controls the relative proportion of time that the device stays on. Set the thermostat midway, and the device is on about half the time; set it all the way up and the device is on all the time. Hence, to heat or cool something most quickly, set the thermostat so that the device is on all the time. The valve theory proposes that the thermostat controls how much heat (or cold) comes out of the device. Turn the thermostat all the way up, and you get the maximum heating or cooling. The correct story is that the thermostat is just an on-off switch. Setting the thermostat at one extreme cannot affect how long it takes to reach the desired temperature.

People’s mental models of heating systems are often stereotyped or played with (as we’ve discussed before here), but as Willett Kempton found out in a classic study, there are some nuanced versions of the theories, which, in practice, are perhaps not as silly as Norman suggests. People satisfice.

Say you come in from outdoors, and are cold. Because of the delay in your exposed skin warming up to room temperature, it surely does warm you more quickly if you stand near something that’s hotter than you actually want to be, e.g. a log fire / stove. So the heuristic of ‘turning up the heat to more than you need, in order to feel warmer more quickly’ is pretty understandable, especially when the temperature controlling the thermostat is the temperature of the thermocouple/probe/whatever and not actually the body temperature of the users themselves. (That would be a good innovation in itself, of course!) Am I wrong?

Given that a lot of people do try to control heating systems as if they worked on the valve model, would it be sensible to develop one which did? Do they already exist?

*Rattle’s second ‘Design Monday’ session, on ‘Lunch’, is also well worth a look.