Modern Building Services

16 MODERN BUILDING SERVICES SEPTEMBER 2022 FEATURE ZERO CARBON BUILDINGS B uilding services are under scrutiny in the commitment towards net zero: the sector accounts for almost 30% of carbon emissions in building & construction in a well-insulated building, and ventilation and cooling may account for more than 50% of the energy requirement 1 The operation of buildings itself accounts for between 18% and 28% of the UK’s emissions and the built environment in total up to 25% 2 . The places where we work and play - including offices, factories, hospitality, and retail- represent 70+% of non-domestic energy consumption. We must not forget embodied carbon- the GHG emissions associated with building construction, including those that arise from transporting building materials to the site, as well as the operational and end-of-life emissions associated with those materials. Buying British not only improves sustainability but helps offset the impact of rising transport costs. Even considering the materials from which the various components are made can help: aluminium, for example, can be infinitely recycled. The problem the construction industry faces currently are that it is not geared up to efficiently deal with the recycling of materials when a building reaches the end of its life- but that’s a topic beyond this! To focus on the building services, we are lucky in the UK in that our (current) climate is ideally suited to optimise the use of energy-driven systems. With amildmaritime climate warmed by the gulf stream, we experience cool, wet winters and warm, wet summers, rarely featuring the extremes of heat or cold common in other climates. This limited variation in extremes enables us to reduce our need and dependence for cooling and ventilation onmechanical solutions. A further consideration is that, as we build tighter, we improve the thermal performance of the building: less energy to heat, but a greater requirement to cool/ventilate. Added into the mix are changes to our Building Regulations- the best practice guidance we should endeavour to follow, which have been updated with implementation this year. Part L- conservation of fuel and power and Part F- ventilation. The driver behind updates to Part L is inevitably carbon reduction. Part F similarly reflects this, but also addresses indoor air quality (IAQ), with a baseline for offices set at an airflow of 10l/s/person or 1l/s/m 2 floor area, with CO 2 monitoring and reduced ducting lengths. We further need to factor in Indoor Environment Quality (IEQ) which brings noise and air movement into the mix. These need to be considered in conjunction with the relevant CIBSE guidance- specifically AM10 and AM13- and other sector-specific documentation such as Health Technical Memorandum (HTM) 03-01 for healthcare facilities and Building Bulletin 101 for schools. All, as a result of the carbon zero objective, are increasingly advising the use of natural ventilation, in a whole building approach, where “reasonably practical”. According to HTM 03-01, mechanical fans alone use 40% of all electricity consumed in ventilation. The preferences for ventilation strategies now are, in order of priority: 1. natural ventilation 2. mixed mode 3. mechanical ventilation To achieve a reduction in the UK’s carbon emissions, we need to look at BOTH the means of heating, cooling and airing a building, and our sources of supply says Roy Jones, Technical Director at Gilberts Blackpool. The role of ventilation in the carbon net zero revolution