OPINION Your views from across the built environment
BAD BY DESIGN
Over-complicated models and regulations hinder rather than help in the quest for energy efficiency, argues Becci Taylor
by spending that time on facilities training or user education, then the modelling is not working. Building Regulations Part L uses
Engineers need to use energy modelling to innovate rather than to tick boxes
A recent remark from an engineer prompted me to
wonder about the extent to which the need to score sustainability points or apply energy models can detract from a key purpose of good design – to optimise the energy performance of buildings. The engineer in question remarked
that ‘we don’t get points for that in LEED, so there is no point’. His comment related to the LEED credit that can only be awarded if 75% of spaces achieve the required daylight factor (the equivalent requirement in BREEAM is 80%). This means that, if we can’t get 75% of spaces daylit, we may well just settle for 60%. I have recently been working on buildings outside of the UK, where the client has not been interested in LEED or BREEAM but wants an intelligent approach to sustainability. We made design decisions based on the operational patterns of the building and on regional priorities, even if this went against the spirit of regulations or gained no sustainability credits.
16 CIBSE Journal July 2012
Such decisions included, for example, a whole-year approach that benefits systems usage: we demonstrated that variable air volume (VAV) systems with relatively low percentages of fresh air were more energy efficient without heat recovery (in a warm climate). Building regulations that prescribe usage patterns don’t encourage this approach. I absolutely support the use of
analysis and energy modelling to optimise the energy efficiency of buildings. But I want the industry to use it to innovate and come up with better ways of doing things in response to specific constraints or opportunities. At the whole-building scale, the impact of occupant profile, behaviour, and plug loads is so large that we must question the use of dumb yet complex whole-building energy models. If the modelling is complex, the
results and methodology must be robust, repeatable and representative of reality. And if the time devoted to modelling can save more energy
Engineers need to truly consider what energy modelling is for
the most complicated and least transparent means of assessment of all regulations. How is this beneficial? Can’t we be given more freedom to design better without designing to perform only in models or tick boxes? The carbon metric used by the Department for Communities and Local Government to evaluate building performance is also open to question. Energy consumption is both a building design and an operational issue. Energy supply and its carbon intensity is a national and policy issue. As building services designers, we should be thinking in terms of the former – that is, thinking in kWh. The tools available to us have been developed for the right reasons, but manipulated in both approach and intention to be used for regulatory reasons. Using whole-building energy modelling to apply a single solution is an approach more appropriate to accountants than engineers. However, using modelling as a design tool by taking an element of a building and testing various options is a powerful design tool. Building services engineers need
to fundamentally consider what energy modelling is for and in whose interests. Of course, building regulations must be met and BREEAM points achieved, but we should also ensure that clients end up with increasingly better, more efficient buildings that operate as intended. Engineers should be striving for
more sustainable buildings through design, not point scoring. Becci Taylor is an associate at Arup
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