Friday, 31 January 2014

Energy saving in a rented office - experience

My friends have a small business which recently outgrew their home office and so they rented a small office in the city - I won't say where to preserve anonymity but it is a 2-storey building split into a number of office units on a business park. They moved in at the end of August and they were dismayed at how warm it was. Weeks went by and the weather turned cooler but the office did not. They tried turning off the radiators but it was still too hot. There was more than enough heat coming from the uninsulated hot water pipes going to the radiators, never mind the radiators themselves - the pipes were hot enough to burn your fingers on. The other tenants seemed to control the temperatures by opening windows. The rent included services so they were effectively all paying for the unwanted heat - but hey, gas is cheap.


My friends spent £80 on insulation for the hot water pipes in their office but they were still too hot. One day when it was 14C outside they recorded 29C inside. Opening the windows helped but caused an uncomfortable draught, quite apart from the wasted heat.

They borrowed my thermochrons (see also Energy Savings by not heating the spare room) to monitor the temperature in the office continuously for a week. The chart below shows some of the data they recorded – along with external temperature data from a local weather station.
Temperatures recorded by the thermachon buttons over 7 days



There are several interesting conclusions to be drawn from this.
  • The heating was continuous overnight. If the heating had cut out the difference in temperature would have reduced through the evening and there would be a sudden increase when it restarted the following morning. In fact the temperature drops little overnight and the increase in the morning is quite gradual.
  • The building temperature is largely unrelated to the external temperature. Even when it got very cold on Sunday morning there was no particular drop in temperature. That also supports the conclusion that the heating is on all the time.
  • The office temperature peaks in the afternoons where as the corridor does not. Also there is no afternoon peak at weekends. That suggests the afternoon peaks are due to activity in the offices – people and the computers, printers and other appliances they run.
The building is maintained by a management company but my friends' complaints were fobbed off so they went direct to the landlord. This is an organisation which is keen to promote green credentials. My friends used the data from my thermochrons to back up their story. Regarding the overnight heating, apparently, this regime had been established as a temporary measure some time before and was supposed to have been reverted back to normal - but it had not. Some men were sent to fix the problem; when they arrived they had to go hunting for the thermostat as they did not know where it was.

Another problem is the windows in the ceiling of the atrium. The atrium is the height of two stories plus the roof so they are at least 7m above ground. They are opened and closed by motors controlled by switches at ground level. It is hard to see the position of the windows, partly because of the height and partly because there are other structures in the way. If you keep the open switch on when they are already open as far as they will go the motor burns out trying to push it further - this happened to at least a third of the windows so the motors would not close them any more. The atrium was chilly (relative to the offices at least) but the radiators in there were still full on - so hot as to burn your fingers if you touched them.

When my friends complained about the windows the landlord said they were aware of the problem in the past but they were under the impression it had been fixed. The problem has now been rectified by screwing the offending windows shut. However, this will probably cause a different problem in the summer when the offices are at risk of overheating. A more intelligent motor that cut out when the window was fully open or closed, or even a thermostatically controlled opener, would be a more enduring solution.

Overheating is a common problem in buildings with multiple occupancy with all-in services. The building management wants to make sure everyone is warm enough, even if this means some are too warm. The contractors who are sent in to maintain the building don’t know it well enough to fix it properly. Getting things changed is so difficult it is easier for the tenants to manage their comfort by opening windows than by complaining to the management, even though it increases everyone’s bills. In this case persistently nagging the right people got some improvement though the new regime is far from perfect.

Now read part 2 of this story: Gas use in tenanted office halved

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