OPINION
Your letters Real-life data is good for 3D models
This month: Combining passive and renewable solutions, bringing 3D to real life, and online reaction to the CIBSE lecture
Call the professionals In reply to Catherine Applegate’s letter, I would suggest if we, as a profession, allow people who mend washing machines, install insulation, mend cars and clean drains out to call themselves engineers, then we deserve all we get. It does not happen to lawyers and accountants. The governing body of those professions will not allow it to happen, but we allow anyone to be called an engineer and that is the real issue. P. Childe, Leeds
Not a CIBSE professional
that control by ensuring both that performance is continuously monitored and that a good design intention is understood and fully adopted by the building users, owners and operators. So, why are the models different?
During design, as model input data can never be entirely known, you are working with assumptions, across elements such as weather data, occupancy, equipment usage, equipment efficiencies, and building fabric material choices. As the design progresses, the number of assumptions fall, but not all of them. At the design stage we are simulating to establish a potential for performance, not emulating the actual performance. At compliance, model data – be it
Bringing 3D into the real world Worrying about energy analysis differences between design, compliance and operation is a red herring. The models are completely different. Trying to compare them is a pointless exercise as it’s not a like-for-like situation. By spending too much time preoccupied with these differences, we are not tackling the major issue – that of ensuring the intentions of good design are followed through into operation. The industry must begin to safeguard
16 CIBSE Journal December 2012
UK NCM, ASHRAE 90.1 or any other flavour of regulation or voluntary rating system – must ensure consistency for all practitioners. This leads to prescriptive methodologies of calculation, standard weather data, occupancies, and equipment usage; the aim being to produce an energy performance certificate, for instance, that can be fairly compared against some national benchmark. This required consistency means that a compliance model, by its very nature, is definitely not emulating actual performance, and may not even be the same as the design model. When dealing with buildings in operation you have access to the real- life data; weather, occupancy, internal
Building Regulations play ‘catch up’ and are never ahead of real requirements
conditions, energy usage and so forth. This allows you to calibrate the 3D building model to real life, providing a benchmark against which to analyse and review performance. This way you can uncover hidden savings that review and interrogative building management system data alone just cannot discover. On a recent project we achieved a 20% reduction on the annual energy bill without any capital spend. However, you can also use this approach to identify best renovation energy conservation measures, and track and prove associated financial savings. Let’s move the debate on and start to understand how we can ensure good design intentions are followed through. Craig Wheatley, IES
Passive, renewables or both? In the November 2012 Journal, several letters, articles and references debate the Green Deal. Elsewhere in the same edition, Passivhaus is championed (by Bruce Tofield and others). At the CIBSE Conference and Exhibition, Paul Morrell said ‘change is coming – the future is here’. But is the future a Green Deal or a Passivhaus/ EnerPHit home? In fighting for one or the other, observers and protagonists may lose sight of the principal aim – to save energy. We are in debt to energy companies.
The industry has morphed into an oligopoly. These companies do not need to compete persuasively for our captive patronage, but only to focus on shareholder value and agency rewards. The only way to reverse this and to lower the price of energy is to stop wasting it. What is the mechanism for achieving
this? Building Regulations play ‘catch up’, and are never ahead of real requirements; coding levels are market- driven options; the Green Deal is aimed primarily at reducing fuel poverty, not eliminating energy consumption. None of these has fully grasped the energy ‘nettle’ – we must all increase its redundancy by cutting consumption to the minimum.
www.cibsejournal.com
HINTAU ALIAKSEI / SHUTTERSTOCK
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