Greenlines Issue number 37, Sept 2013
The University’s sustainability newsletter
Staying warm at Cambridge
ISBN: 2048-2442 (Online)
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MONTHLY
Inside this issue: Staying warm at Cambridge From inside a Department Meet the Environmental Officer Living Lab Seed Award Green Impact Ethical Guide
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Over at Environment and Energy, we’ve already been feeling the chill – and with memories of a gloriously sunny summer already fast-receding, many people’s thoughts may be turning to the question of how to stay warm throughout autumn and winter, particularly those residing or working in the university’s older buildings. Did you know that the university has drafted a thermal comfort policy? The policy states: “Human perception of a comfortable temperature is subjective. It is based on a combination of factors including; air temperature; radiant temperature; humidity; individual metabolism and clothing.” So what does all this mean exactly? Air temperature is pretty selfexplanatory – and with the new Green Impact thermometers it’s easy to tell when it’s getting a bit nippy. The University policy is to heat between 1921°C during the heating season, which usually starts in October and ends in April. But air temperature is only one of the things which affect overall thermal comfort – and it may not be the culprit if you’re still feeling chilly. Even with the heating on, an office with lots of air changes may struggle to reach the desired temperature. Essentially this means that as fast as air is heated
Wear your jumper to work day held during Switch Off Week 2013
by your radiators, it is leaving the room as a result of draughts, or the frequent opening and closing of external doors. Try to trace the source of draughts and you might find you can address the problem yourself such as by keeping doors closed or rearranging the office furniture. Note that windows can also cause localised draughts, by cooling any air which is next to them – this air then sinks to the floor and ‘slides’ across the room, creating a draught (to counteract this, radiators are often placed below windows). Have you ever wondered why you can feel warm on a cold but sunny day? Radiant temperature is the answer – the sun’s rays hitting your skin, making you feel warm, even if the air
temperature is low (a campfire works in the same way). Or more scientifically, a warmer body (the sun) will radiate its heat towards a cooler body (you). Unfortunately, in many of the university’s buildings – particularly the older ones – the warmer side of this equation tends to be you, which means you end up radiating your body heat to any particularly cold surface that may be nearby (usually a window) and this can make you feel cold, even if the air temperature is warm. So how to fight this evil trick of physics? Firstly, invest in a good jumper. This may sound trite but it makes good sense – it’s far more straightforward to insulate your own body, than insulate the room you occupy. By covering exposed skin, the
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