UK legislation requires that many large buildings display a certificate, updated every few months, that shows "how efficiently the building is being used".
This mandatory certificate could have been used to communicate information to people, and to engage the building's users in the challenge of improving the building's energy consumption. However, it seems to me that the designers of the certificate have almost completely blown it: the certificate's main features looks fairly colourful, but they convey amazingly close to no information at all.
How much information can be conveyed on a sheet of paper? One of the simplest principles of communication is that the message should depend on something; the message should not be fixed in advance. For example, Lord Nelson, at sea, had a collection of a few dozen flags from which he could select some to run up his mast. Which ones he ran up his mast depended on what message he was intending to communicate. Someone looking at Nelson's ship would not know in advance what the flags would look like.
This communication principle is almost entirely lost from Display energy certificates: the look of the certificate is almost entirely determined and fixed before any building data are collected.
The most prominent feature of the certificate is the "A-to-G" scale, with its green-to-red/brown colour scheme. Almost all the numbers on this scale are fixed; the only adjustable piece is the little arrow that points at "how well this building is being used". This performance is measured in meaningless pseudo-units, with "100" corresponding to "average for buildings of this type". This number can't be compared, from building to building, since two buildings might be of different types, and the certificate doesn't say anything about the type. Nor can an ordinary person work out what the number means, nor what they should do about it, because the number can be computed only by experts using the government-approved software that churns out these certificates. (I've looked on government websites, and have been unable to find any definition of the magic formula for computing the number; I imagine I would have to pay to attend a government-sanctioned course in Display energy certificate cookery.)
The second feature of the certificate is the top-right blue rectangle. Again, this object achieves amazingly little communication. It is meant to show how much CO2 the building's use is emitting. I would like to make a prediction: I predict that, on the first certificates displayed in the year 2009 in all the thousands of buildings across the country, every single certificate will have a blue rectangle of exactly the same height!. I make this prediction because it looks to me as if the government-sanctioned standardized software auto-scales the entire blue rectangle so that it has got a standard size! Therefore the only way to find out the CO2 emissions of the building is to look really closely at the scale of the graph, which shows, in the smallest font conceivable, an absurdly long number, at the top of the vertical axis, partly overlapping the axis. This absurdly long number, I would guess, is the actual CO2 emissions. In my photo I think it shows 26095 tonnes of CO2 per year. If someone ever manages to read this number (please bring a magnifying glass!), will it mean anything to them? Is a typewritten number a good way to convey information? Is it a good idea to show five decimal places of precision? When communicators discuss how to label the axes of a graph, does anyone recommend that the six tics on the graph should be labelled (nothing), (8693), (nothing), (17396), (nothing), and (26095)?
The one interesting fact that is well conveyed by the blue rectangle is the breakdown of CO2 emissions between electricity and heating: the top (light) half of the blue rectangle shows the electricity contribution, and the lower (dark) half shows the heating.
And finally, the third prominent colour element in the display is the "Previous operational rating" graph (bottom right, orange), which shows "how efficiently energy has been used in this building over the last three accounting periods". At present (in early 2009), this colour object conveys no information at all as it shows only a repeat of the energy performance rating displayed on the left-hand side. In due course, maybe it will reveal an interesting trend, but it will depend on the choice of "accounting period". Is the accounting period going to be one year? If so, the comparison of last year with the year before will be meaningful, but is it going to engage users? Imagine if, every day when you entered your building during 2009, the porter informed you what the total energy consumption had been in 2007 and 2008. Would these facts interest you in putting effort into efficiency drives? I fear that a yearly update is too long a timescale for any useful engagement to happen. On the other hand, if the "accounting period" lasts, say three months, then the variation in operational rating from quarter to quarter would be entirely dominated by seasonal effects. My guess is that the certificates will be updated annually, so building-users will become completely blind to the certificate. The opportunity for user engagement is almost entirely lost.
What have we seen so far?
Does the certificate have any useful information on it? Yes, hidden away in tiny print at the bottom left hand side are interesting numbers - at least to building energy specialists. The "technical information" shows, in a table, the energy use (heating and electrical), expressed in the meaningful units of kWh per square metre per year. And to make this energy use comprehensible, the table also specifies the "typical use" (of buildings "like this", I presume).
What could have been done better?
As far as I can tell, the entire piece of paper is really conveying
just two numbers:
|`this building's heating consumption is:||519 kWh/m2/y';|
|`this building's electrical consumption is:||44 kWh/m2/y'.|
How could the certificate be better? Well, the certificate could have been better in two ways:
Government explains DECs