Notre Dame is a voluntary aided Catholic girls' school based in Southwark, central London. The building has a number of areas where overheating is a problem for a variety of reasons, these include; external heat gains, changing usage patterns and additional heat loading within the space due to computers and other equipment.
A number of problem areas already had split air conditioning systems installed to provide cooling. However due to concerns about running costs, sustainability and the difficulty of mounting external units to the outside of the building, the school were looking to trial alternative solutions that were easy to retrofit. No mechanical ventilation systems were used in any of the classrooms, the only ventilation provided was through the opening and closing of windows.
Two COOL-PHASE systems were installed in an IT classroom in April 2011. The classroom (approx. 70 sq m) has high internal heat gains with 30 PCs and an overhead projector, while partly shaded windows on two sides create 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 with 30 PCs and an overhead projector, resulting in similar internal heat gains. Due to external gains from SW facing windows, there was higher external heat loading than the classroom where COOL-PHASE was installed. This classroom had a Split Air Conditioning (AC) system already installed to provide cooling.
The second control room was a 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 to compare performance to. Temperatures and CO2 levels were monitored during the Spring term prior to the install to enable the two IT classrooms to be compared.
The average temperature in both environments during the spring term are very similar. This shows both rooms have very similar internal heat loading. The average temperatures increased in the control room slightly between the spring and summer term as can be expected due to warmer weather.
However the room with the COOL-PHASE system has not replicated these trends and instead has seen a significant reduction in the average temperatures before and after the install. Despite the differences between the rooms, it is clear that the COOL-PHASE system has had a significant impact on average temperatures. A similar pattern can be seen for the CO2 levels. The results before and after the install of the COOL-PHASE system showed a very significant reduction in the number of hours where the CO2 levels exceed 1500ppm.
The room with the COOL-PHASE systems installed, has shown better performance than both the control rooms. Despite having lower heat loading, the Geography classroom has 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. Surprisingly the classroom with the COOL-PHASE systems has also shown better results than the IT classroom, which despite having higher heat loading also has an Air Conditioning (AC) system installed.
The temperature gradient resulted in some areas being overcooled and complaints from children nearby. The AC system would then be turned off and the temperatures left to rise until high temperatures caused it to be turned back on again. Since the only method of ventilation was to open the windows this would also have contributed to higher temperatures.