By David Leatherbarrow, Director of SAS International.
New build projects gracing our landscape today are not just setting their mark in the style stakes but also in the adoption of new and innovative technologies to provide comfort cooling.
Whilst new builds set the bar high, as they provide project teams with a great opportunity to fast track knowledge, refurbishments of buildings should not mean that innovation is ignored.
Drivers for change not only include legislation and government targets but also end clients who are demanding that things should be done differently. Demand for long-term value is coming to the fore with occupant comfort increasingly being recognised as enabling productivity in the workplace.
Since the 1960’s almost every commercial and institutional building in London has been air conditioned. It’s not just due to fashion or increased luxury but it is a necessity due to the intensive use of buildings, with high occupancy rates and heat generated from office equipment and lighting.
Add to this the trend in architectural design for fully glazed buildings which allow more solar radiated heat to penetrate the building and the fact that they are more airtight and it is easy to see how many modern buildings no longer require any heating at all, except during exceptional winters or when resuming work after a winter break.
So what can be done about energy requirements for air conditioning to meet modern demands? For 40 years two systems dominated the institutional office market Variable Air Volume (VAV) and Fan Coil Units (FCU), but for the last 15 years lower energy solutions have been available in the form of chilled ceiling and chilled beams.
But why should these solutions be a preferred choice? Both require less input energy per Kw of cooling achieved than previous systems, which answers sustainability demands. They utilise water as the heat transfer medium, the circulating water is also at a temperature above the dew point of the space therefore requiring less energy to cool the water.
As with most technology choices for refurbishment projects a number of factors lead to the choice of chilled beams and ceilings. These solutions radiate cooling downwards and provide quiet, draft free comfort cooling to occupants.
In addition operational savings occur because chilled beams use higher chilled water temperatures than traditional cooling systems. This has the advantage that it allows the chillers to operate more efficiently and to take advantage of free cooling for much of the year. The raised water temperatures also enable renewable solutions such as ground water cooling to be considered.
Chilled ceilings and beams allow engineers and architects to answer the demand to deliver the cooling performance required to combat the heat loads and can also meet acoustic demands needed for enhanced occupant comfort in a commercial environment, through their quiet operation. And, as chilled beams can be controlled via individual building zones they can count towards efficiency targets.
Meeting modern demands
Air conditioning was not an issue when energy was relatively cheap and the environmental and economic impact was not yet part of the agenda. Although the professional team did their very best to reduce the building’s energy footprint everything was judged on an investment payback and most improvements were discounted – saving energy did not save enough money to justify the capital investment.
Energy is no longer cheap and the environment can no longer sustain the impact of this level of energy usage to circulate, cool and control using multiple pumps and refrigeration compressors. This has changed everyone’s attitude and energy awareness has been heightened even before the advent of Part L of the building regulations, which have in turn been tightened up.
Research commissioned by the British Council for Offices (BCO) revealed that the office sector will continue to be shaped by increasingly rigorous environmental legislation, making the risk of existing stock becoming obsolete even greater. Core findings include that increasingly stringent environmental regulation will have a growing impact on architects, developers and occupiers, whilst also having a knock-on effect on investment in commercial property.
With this in mind project teams need to be innovating now for the future benefits of their clients. We know that products are driven by price but what is the real value of solutions? Is it for short term or long term? Will it allow flexibility for future change of occupants or legislation? Products installed today will need to meet demands of occupants over a 50-60 year building cycle.
Chilled Beam solutions can very effectively be factory fabricated into larger ceiling modules containing lighting and sensors. These can meet the higher standards of factory quality and also be tested as a unit prior to delivery and installation. Due to the increased size of the M&E module being installed and the factory pre-testing, the construction programme can also be significantly accelerated.
Ease of maintenance for any solution will of course help in the long run as systems last longer. Maintenance costs for chilled beams also tend to be less because they contain few moving parts. There are no internal fans, no filters to clean, or actuators to repair in the occupied space, which helps ensure a trouble-free operation over their life expectancy. This is essential in an office environment as there is minimal disruption to workers.
BCO research also revealed that 77% of respondents said an unattractive workplace would make them less proud to work for an employer, and half (50%) would have to be paid more than 10% extra to stay in a workplace with very poor offices.
There is still a change of mindset required for many clients, developers and letting agents who know the costs of historic systems and are comfortable with their benefits and disadvantages. Studies have shown for example that chilled ceiling and chilled beam systems are no more expensive to purchase and install, and are inherently cheaper to operate than previous industry standards of Variable Air Volume and Fan Coil Units for air conditioning. Both require less input energy of Kw of cooling than VAV or FCU systems.
Part L of the Building Regulations and the Government’s targets will mean that change is inevitable and as an industry we need to work to new sustainable and efficient standards; and with energy costs on every business agenda right now, the time is right for change.