Modern Building Services

14 MODERN BUILDING SERVICES JUNE 2021 FEATURE EFFICIENCYVS OVER ENGINEERING ENGINEERING T his doesn’t come as a surprise given buildings are responsible for nearly 40%of global greenhouse gas emissions. Inmaking our buildings sustainable and efficient however, there can be a tendency to over-egg the pudding. Assuring technical compliance andmeeting building codes is one thing, yet designing a building’s M&E systems to havemore electrical, heating and cooling capacity than is needed costs more and drives higher energy consumption. To combat over-engineering, which smarter considerations can be utilised to ensure building services perform as designed and create an optimum environment for all? Over-engineering has a significant impact on the cost and performance of a building project or scheme, particularly in terms of efficiency. Signs of over-engineering can manifest themselves in a variety of ways; from plant cycling to uncomfortably warm spaces, to slow pump speeds and stop-start chillers. These inefficiencies have a draining effect on a building’s performance and occupant comfort, and can also negatively impact a building’s green credentials. How does over-engineering occur? Over-engineering can occur for many reasons, but the majority of the time it can be as a result of human behaviour. We are, arguably, predisposed to err on the side of caution when there is a certain degree of risk. Where there are ambiguities, human beings will over-compensate, just to be sure they have shielded themselves against anything that has the potential to cause any damage. The same can be said for construction projects; under- designing is known to affect companies’ insurance claims, so for engineers it is no wonder they make certain concessions, giving a 20% leeway just to be sure. This leeway however, isn’t something done arbitrarily but grounded in the building regulations. Publications such as the 18th edition of the NewWiring Regulations, known as BS 7671 published by the IET, recommends an additional 20% capacity for future uses. Whilst this capacity has been enshrined in building regulations, its implication on over-engineering is problematic. The extra capacity currently implies that electrical networks are being designed 20% larger than they need to be and based on potential forecasts. By project completion, if we apply this principle to all building services, these incremental increases create a massively over- engineered building that could be avoided if exact figures were ascertained. At the moment, the current practice is resulting in high degrees of inefficiency. To challenge this systemic issue, changemust come fromwithin. Some degree of commonality needs to be identified so designers can make their calculations with as much reliability and accuracy as possible. Alex Hill , Managing Director, Whitecode Design Associates says “building performance and efficiency are increasingly under the spotlight as a result of themove to carbon neutrality.” Over-engineered buildings put a dent in efficiency