BSEE


CHILLED BEAMS & CEILINGS


Could integrated HVAC systems be the UK’s cooler future?


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Andrew Gaskell, chairman of the Chilled Beams and Ceilings Associaon, suggests we follow Australia’s lead when it comes to integrang HVAC systems into the design stage of buildings to improve energy eciency


n 25th July 2019 the UK experienced its hottest day on record, peaking at 38.1˚C in


Cambridge. Just a


day before, CIBSE held a seminar in London, titled “Avoiding overheating”, during which CIBSE head of research Anastasia Mylona and technical manager Julie Godefroy discussed revisions to Approved Documents F and L, as well as the causes and risks of overheating buildings.


Although many people may have enjoyed the hot weather; dehydration, breathing difficulties, heat exhaustion and heatstroke are just some of the dangers that can put people’s lives at risk during periods of extremely high temperatures. Poorly installed, maintained and controlled HVAC equipment, as well as inadequate natural ventilation can drastically increase the chances of a building overheating, which can result in serious health concerns for the building’s occupants. The importance of ensuring a healthy indoor environment while remaining compliant with modern energy efficiency demands is an ongoing challenge for building managers. Commercial buildings typically undergo many changes over the course of their lives. Tenants will come and go and every new occupant will have their own ideas on setup and working environment. The building owner or operator will need an HVAC system that can offer long term flexibility on top of long term energy savings. However, the way we approach building design in the UK makes it difficult to achieve optimum energy efficiency during a building’s lifetime – as our Building Regulations focus primarily on the design and technology that improves predicted building performance for purely compliance assessment, instead of achieving directly measureable improvements in performance in-use.


Different Down Under


We enjoy a great sporting rivalry with Australia, as demonstrated by the thrilling 2019 Ashes series. The series was tied, but away from sport, when it


comes to energy efficiency in buildings, our Aussie friends are some way ahead of us. Their ‘NABERS’ (National Australian Built Environment Rating System) introduced and implemented over the turn of the 21st century, is a performance-based rating system for buildings. A NABERS rating for a building is based on a methodical assessment of the actual environmental impact of operating it and has allowed buildings and workplaces in Australia to achieve impressive environmental savings, that we should be examining and learning from. In particular, Australia’s method of incorporating the simulation of HVAC systems and controls at the design stage of a building is something that would really help our drive towards lower heating emissions.


It is always worth reminding ourselves that around 40 per cent of global energy consumption is attributed to buildings, with cooling and heating alone contributing a significant portion of that. We can change that by adopting greater scrutiny of the HVAC system, which we currently lack a basic rating system for in the UK, where we have, for too long, designed our buildings to comply with regulations. This results in the performance gap between original design intent and the reality of how the building performs. In contrast, under the NABERS system, both landlords and tenants as well as other invested parties can use a base building rating to factor in-use energy performance into their decision making.


For commercial premises in the UK, landlords will generally provide a central HVAC service to their building, but the occupiers’ own HVAC systems are then more likely to be outsourced to the tenants themselves, who will also have control of their own building management system. With each


32 BUILDING SERVICES & ENVIRONMENTAL ENGINEER DECEMBER 2019


tenant having their own HVAC system and facilities management team it is very difficult for the landlord to maintain any real control over their building’s efficiency as they are required to keep the central heating system operating constantly. In Australia, while tenants manage the fitout of their own HVAC systems, the landlord maintains oversight over the design and is able to refuse approval of the system if it is likely to negatively affect their building’s base rating.


Beams of efficiency


The diversity and flexibility of chilled beams make them an ideal HVAC solution for a more integrated approach to building design and function. Picking the cheapest system without taking running costs into account could end up proving extremely costly in the long-term. A key attribute of chilled beam technology is an inherent efficiency that can help building operators to slash energy bills, delivering significant savings over an extended time period. Occupant comfort and energy efficiency do not have to be mutually exclusive, the choice of HVAC system should therefore play a more prominent role in the design stage of a whole building, instead of being considered separately. Modern commercial buildings require a modern approach to cooling, heating and ventilation, and multiservice chilled beams (MSCBs) are capable of providing a full range of services to meet specific user requirements. Also, chilled beams can work well alongside other energy efficient technologies such as heat pumps to offer a practical long-term heating and cooling solution.


‘


Poorly


installed, maintained and controlled HVAC equipment, as well as inadequate natural venlaon can drascally increase the chances of a building overheang, which can result in serious health concerns for the building’s occupants


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