The thermal batteries are mounted in a module containing a heat exchanger. This allows heat to be transferred from the air to the thermal battery, or vice versa. Modules can be placed wherever cooling is required and are connected directly, or via a duct, to the air handling unit and ventilation system The air handling unit (AHU) contains


an intelligent control system, fan, damper and filters. The control system monitors indoor air quality, as well as temperatures both inside and outside, and controls the fan and dampers. The AHU controls the flow of fresh air into the building, re- circulation of air within the building, and how energy is released or stored within the thermal batteries. The filter removes particles, allergens and pollutants from the incoming air. During summer nights cool outside air


The CIBSE Building Performance Awards recognise, reward and celebrate the best performance, innovation and practice in design, commissioning, construction, installation and operation of sustainable buildings and the manufacturers whose technologies enable energy efficiency. For further information on this year’s winners, as well as details of how to enter the 2013 awards, please visit www.cibseawards.org


is passed through the heat exchanger to recharge the thermal energy store for use the next day. As temperatures rise, warm air is passed through the heat exchanger to provide cooling. The total cooling provided is a combination of the thermal energy stored within the unit, the effects of free cooling and night-time ventilation. In winter, Cool-Phase works in reverse, trapping waste heat and using it to warm cool fresh air entering the building. The system works all year round to ensure a fresh and healthy environment, monitoring temperatures and CO2 levels to automatically determine how much


ventilation or cooling is required. Of course, there are other thermal energy


store solutions open to designers, not least the inclusion of exposed concrete in the building’s structure, which can then be similarly used in conjunction with night-time ventilation to control internal temperatures. Yet, Cool-Phase, while also suitable for new build, is perhaps particularly attractive as it can be easily retrofitted, whereas concrete is only a solution for new projects, extensions or major refurbishment. Monodraught hopes Cool-Phase will


prove popular in commercial office areas where clients may wish to have a greater level of control over internal temperatures than natural ventilation offers, but without the energy costs and ongoing maintenance costs associated with conventional air conditioning systems. Similar arguments apply in the retail and healthcare sectors. Schools are also a target market. Over


recent years there has been a great deal of research into the optimum teaching environment. It is generally accepted that internal CO2 levels should not exceed 1,200 ppm and design guides for school design state a maximum average of 1,500 ppm. Cool-Phase systems include CO2 monitoring as standard and control the level of fresh air within classrooms to provide the ideal teaching environment. ‘Demand is really starting to take off, not just in the education sector but also


Case study Lessons learnt at Notre Dame School CO2


The Victorian Notre Dame School in Southwark, London, had a number of areas where overheating was a problem because of external heat gains, changing usage patterns and additional heat loading due to computers. A number of problem areas


already had split system air conditioning units installed to provide cooling. However, due to concerns about running costs, sustainability and the difficulty of mounting external units, the school was looking to trial alternative solutions that were easy to retrofit. Two Cool-Phase systems were installed in an IT classroom in April 2011. The 70 sq m classroom had high internal heat gains with 30 PCs and an overhead projector, while partly shaded windows on the north-west and south-


46 CIBSE Journal May 2012


Temp >25(˚C)


Control-IT Classroom


Control- Geography Classroom


COOL-PHASE


Temp >28(˚C)


>1000 ppm 69.8% 6.1% 58.2% 59.0% 2.3% 39.5% 2.3% 0.0%


east elevations meant the room suffered from solar gains. Two control rooms were chosen in order to provide a comparison to the performance of the Cool- Phase systems; the first was another IT classroom, also with 30 PCs and an overhead projector, resulting in similar internal heat gains. Due to solar gains from southwest-facing windows, there was a higher heat loading than the classroom where the Cool-Phase units were installed.


5.0%


CO2


>1500 ppm 44.0%


14.9% 2.2%


CO2


>2000 ppm 31.7%


6.4% 1.3%


This classroom had a split-type air conditioning system already installed to provide cooling. The second control room was a geography classroom with much lower internal and external heat loading. This classroom had a single PC and overhead projector. The room was chosen as it was located next to the room with the Cool-Phase systems and would provide a baseline with which to compare performance. Data logging equipment


was installed in each of these classrooms. Temperature and CO2 levels were monitored every minute. The data loggers were installed in February 2011 during the spring term, so that the two environments could be compared before the Cool-Phase systems were installed.


The room with the Cool-Phase systems installed has shown better performance than both the control rooms (see table). Despite having lower heat loading, the geography classroom had temperatures above 25C for 59% of the time, while in the room with the Cool- Phase systems this was reduced to just 2% of the time. Furthermore, the classroom with the Cool-Phase systems has also shown better results than the other IT classroom which had the air conditioning system installed.


www.cibsejournal.com


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72