OPINION Your letters
This month: Automated window shading can provide significant savings
Shades go up on quick wins As a new CIBSE member, I read with interest my first copy of the Journal. The cover feature on ‘Quick Wins for Energy Efficiency’ (November, page 40), included presence detectors for lighting but made no mention of window shading or automated shade controls (although the cover illustration does show what appear to be shaded windows). By using solar shades with a solar
screen fabric, up to 50% of heat can be stopped from entering the building. If automated real-time window controls are also used alongside a lighting management system, the same IT backbone and server systems can be used, cutting costs further and providing integrated window and lighting control management and reduced energy costs. For example, in the US the Lawrence
Berkeley National Laboratory (LBNL) monitored the New York Times building for a year after it was occupied in 2007. The LBNL found that a huge amount of energy was saved by using
shades operated by an automated real- time window management system, where radiometers monitor sky radiation. The monitoring showed that, for
91% of the time, the shades operated according to the programme. Of the other 9% of the time, nearly half of the control movements sent the shades upwards more. This was the opposite of what most people had predicted. I look forward to further articles
i0522-30 Air Curtains AW_CIBSE Magazine 190x66 12/10/2011 09:25 Page 1
where, at long last, shades and shade controls are taken seriously by the MEP and the engineering and specification community, as a contribution to sustainability in the built environment. Maggi Clayden Vice-president, MechoSystems UK
Engineering economics The cover story on the London Olympics energy plants says little about the engineering economics of these projects, which is essential to understanding how they work (August Journal, page 16. It is certain that Cofely required, and got, long-term guarantees of payment for the capital and operating costs of those services before proceeding to spend £113m. The article should have shown who provided those guarantees, their basis, and duration. Almost certainly, the prices for those services must also cover the many risks that exist. For example: who pays Cofely, and how much, if the expected occupancy after the Olympics does not materialise? What happens to prices of these services if the cost of fuel changes dramatically? Who will be saddled with these costs? This information is required to make any project proceed and should be published. Larry Spielvogel Bala Cynwyd, Pennsylvania, USA
Who pays Cofely, and how much, if the expected occupancy after the Olympics does not materialise?
Olympian expectations Reading Roger Courtney’s article on urban heat supply, I wonder whether he looked at the article on the London Olympics energy centre in the same issue (August Journal, pages 16 and 34). In this article he would have noted that the average heat loss in the district heating network is (a very low) 1C per km (assumed to be measured at full flow rate, but which will mean higher losses at reduced flow rate). This sounds excellent, until you calculate that this means that the
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