CHILLED BEAMS
climate change ambitions. It is always worth reminding ourselves that
around 40% of global energy consumption is attributed to buildings, with heating alone contributing a significant portion of that. We can change that by adopting a greater scrutiny of the HVAC system, which we have until now been lacking such a rating system in the UK. We have, for too long, designed our buildings to comply with regulations that allow contractors and manufacturers to offer products/HVAC solutions that do deliver the energy efficiencies that are intended/implied. This results in the performance gap between original design intent and the reality of how the building performs (as delivered). 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. The new NABERS UK scheme will help provide connection allowing clients, designers, tenants and contractors to work together to make building perform in operation, reducing energy and carbon emissions. 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 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. The UK Green Building Councils has also
recently published a feasibility study into the design, delivery and cost of Net Zero Carbon buildings which involved a number of industry expert representatives and illustrates how implementing changes to building structure materials, façade, dematerialisation and HVAC system – such as using chilled beams, with demand control ventilation – can be effectively utilized in new commercial buildings to help drive towards achieving Net Zero Carbon targets when compared to current baseline design practices.
The study helps to show that commercial
buildings can be designed today with future Net Zero Carbon Targets in mind whilst helping to understand the associated costs to build a strong case that is does not have to cost a fortune and is likely to be offset by enhanced value (e.g. higher rental capital, lower vacant periods, reduced operational running costs, higher sales price, reduced offsetting costs etc.).
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, product life cycle, maintenance etc... into account could end up proving extremely costly in the long-term. The UK Department for Business, Energy &
Industrial Strategy and Carbon Trust has also acknowledged that Active chilled beams can have both lower operational costs and a longer lifetime than conventional space cooling systems. This is supported by an independent study commissioned by the CBCA (Chilled Beam & Ceiling Association) and carried out by Environment Design Solutions (EDSL) which confirmed a significant energy-saving benefit over alternative technologies. The key to increased 'Energy Efficiencies' is to utilise the water in the system to handle the sensible heat gains and only use the amount of supply fresh air for the respiratory requirements and not for cooling by the air, given that air has approximately one fifth of the ability (coefficient of heat transfer) of water to transfer heat energy out of the building. Using too much air through active chilled beams just makes for expensive air diffusers and uses more energy to provide the cooling.
The other key to increased 'Energy Efficiencies' is to use elevated chilled water temperatures and have further energy savings by being compatible for use with 'Free Cooling' chillers or heat pumps/geothermal. As backed up by the independent EDSL study, all of this results in potential energy savings of 17 to 22% over alternative technologies. Over the entire lifecycle of a commercial building this can equate to thousands of pounds in savings and significantly reduce a carbon footprint. The inherent energy efficiency associated with chilled-beam technology can help building operators to slash energy bills, delivering significant savings over an extended time period. Making buildings greener today can introduce added value and save costs in the longer term (whole life cycle costs) given that implementing design changes now to include for chilled beams solutions would avoid higher refurbishment costs later down the line as associated with other HVAC systems.
Chart Showing Relative Plant Energy Running Costs taken from the CBCA EDSL Independent Study”
However, this requires the industry to implement change over the next few years to deliver higher energy efficient and Net Zero buildings if we want to really strive towards creating a more sustainable planet for the future generation.
www.acr-news.com February 2021 19
ENERGY SAVING
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