AIR CONDITIONING 1 BIOTECHNOLOGY
The RACUS ceiling tile was developed
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for new and retrofit building projects where there is a need to reduce the carbon emissions associated with traditional air conditioning systems, and to give thermal mass to lightweight structures in a passive, easy-to-install ceiling system. It caught the eyes of the judges in the recent CIBSE Building Performance Awards 2012, where it won the Passive (energy-related) Product of the Year category. The product has been extensively
tested, both under laboratory conditions at Brunel University London using its thermal chamber test facility, and at live, independently monitored projects. The testing at Brunel University London examined the effect of the RACUS ceiling tile on the temperature inside a test cell, repeatedly subjected to typical summer day and night temperatures under different states of ventilation in a climate chamber. The test cell was designed to simulate an actual room that contained a 150W electrical heater to provide a cooling load. Results from the testing at Brunel showed that when the RACUS tiles were installed, indoor temperatures were reduced by between 2C and 7C for different ventilation rates, proving that the RACUS PCM tested had an important thermal energy storage potential in ceiling tiles (see Figure 1). But would the product break down
over time? Datum carried out more than 45,000 thermal cycle tests on RACUS to determine the longevity of the bio-based PCM and found no deterioration. This equates to a life-cycle performance of more
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AIR TEMPERATURE AT HIGH LEVEL 5cm FROM CEILING GRID DAY: 25°C, NO VENTILATION, 150W NIGHT: 17°C, 14.9 l/s VENTILATION, 0W
than 122 years. Additional analysis included biodegradability testing, which showed that under aerobic conditions, 100% biodegradability of the PCM occurred in less than 12 months. The binding formulation of the RACUS ceiling tile is made using various natural minerals which, in contact with soil, act as a soil improver and fertiliser. So how has the product performed in practice? Datum was asked by MITIE Facility Management to incorporate the RACUS ceiling tile into two of MITIE’s clients’ buildings so that they could monitor the performance. MITIE was looking at options to meet their clients’ objectives of significantly reducing both their annual energy use and carbon footprint, under the Carbon Reduction Commitment legislation.
Ofcom head office The RACUS ceiling tile was installed into Ofcom’s head office in London. The trial took place in two identical, adjacent meeting rooms, with each room making use of fan coil units to provide comfort cooling. Temperature sensors and data loggers were installed by MITIE, which also recorded the occupancy rates in each room. In one room, 25% of the ceiling area
Air High Level without Tiles
Air High Level without Tiles
Air High Level without Tiles
was installed with the RACUS ceiling tile; the other was left as it was. Over an initial 45-day period, the result of MITIE’s monitoring showed that the fan coil units in the room without RACUS operated for 257 hours, compared to just over seven hours in the room with RACUS. That equates to a massive 97% reduction in energy use – an estimated annual saving of more than £1,520 and 7 tonnes of CO2 per room (see Figure 2). A further seven meeting rooms were installed and monitored and Ofcom was able to turn off the fan coil units completely as the RACUS ceiling tile was able to provide sufficient cooling to maintain comfort conditions. Annual cost savings were estimated to be more than £10,650, with a reduction of 49 tonnes of CO2. This equates to an estimated payback period of 2.92 years. ‘It’s not just about being green,’ says
Mike Berry. ‘RACUS has to perform and offer a competitive payback for clients and it does.’
TIME
Figure 1: Testing at Brunel University London examined the effect of the RACUS ceiling tile on the temperature inside a test cell, repeatedly subjected to typical summer day and night temperatures under different states of ventilation in a climate chamber
Great Ormond Street Hospital RACUS has also been fitted at Great Ormond Street Hospital, London.
40 CIBSE Journal July 2012
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