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With occupied space at a premium in commercial buildings, the flat roof is viewed as a viable space for all kinds of building services equipment, from condensers and chillers to pipework and ventilation. Rob Jackson, National Sales Manager for Big Foot Systems, examines the implications of using the roofspace, and highlights the importance of ensuring that rooftop equipment is correctly and safely positioned.
The space within a commercial building is very valuable. In the office rental market and retail for example, maximising the areas that can be occupied or used for business is vital. Hence plant rooms are often squeezed down to the last square metre, giving designers a real challenge when it comes to finding space for vital building services equipment.
That is one of the main reasons why, when a flat roof is available, consultants and architects often look up to find the solution to their space problem. Placing large items such as air handling units or air source heat pumps on the roof is an excellent solution. As we move to increasing our use of building-integrated renewables, the roof is often an ideal location for technology such as photovoltaics or solar hot water to ensure the best performance.
Careful consideration
However, as with all design solutions, the decision to place equipment on a flat roof surface should be carefully considered and planned. One of the first considerations is the type of equipment being positioned on the roof, and its long-term maintenance requirements. If physical inspection is required, the equipment must be placed where maintenance teams can safely and effectively carry out their work - extremely important when working at height is involved.
For example, since January 2009, air conditioning systems with a cooling capacity of 250kW or more must be inspected annually, and records kept along with the building logbook. From January 2011, air conditioning systems with a cooling capacity over 12kW must also be inspected.
These inspections are largely paper-based, in that inspectors will check over maintenance records. However, where information is missing, a physical inspection will take place. This makes regular maintenance of all areas of the air conditioning system, including those on the roof, even more important.
Phil Ord, Product Marketing Manager for Mitsubishi Electric, says that good maintenance also ensures good system performance: “Simple things like dusting vents more regularly and removing blockages on outdoor condensing units mean that your plant doesn’t have to work so hard, and will consume less energy. Any extra costs incurred by ensuring you have a regular maintenance programme are soon repaid by this reduction in energy use.”
The European Committee of Air Handling, Air Conditioning and Refrigeration points out that air handling units are often thought to be a problem source and even a main contributor to sick building syndrome if cleaning and maintenance are not correctly carried out. As part of its basic requirements, the Committee recommends that: “The air distribution system shall be designed, manufactured and installed in such a way that cleaning of all internal surfaces and components of the AHU is possible.”
While this may seem straightforward enough, the positioning of equipment such as chillers or condensing units does not always achieve these standards. It is not unusual to find equipment placed on some very precarious set-ups, from concrete slabs to bits of wood. This is particularly worrying, because anyone trying to access the equipment for maintenance purposes has to negotiate these obstacles. Big Foot Systems are designed not only to support items such as chillers and condensers safely, but to ensure that they can be maintained correctly as well.
However, while maintenance extends the life of equipment, any technology can only last so long. Therefore, another factor to consider when placing building services equipment on the building roof is how easy it will be to renew or replace the equipment.
Flexibility is key
Many organisations are now replacing older air conditioning systems with newer, more energy efficient models. It’s unlikely that new equipment will fit existing support areas, and may even need to be placed in a different part of the roof. Support systems that offer flexibility are increasingly important. Again, any movement of equipment increases the likelihood of roof damage, so reducing this risk is vital.
Trying to lift concrete slabs is difficult and can easily cause damage to the roof itself. With a non-penetrative roof system, dismantling and rearranging is far simpler. It can even be used to raise equipment over existing obstacles on the roof - giving more flexibility to designers.
One very important point to bear in mind is that a roof does not offer the same robust surface area as a concreted plant room floor. Mike Fox, Managing Director of AWM, a specialist auditing company for the roofing and cladding sector says: “It is very easy to damage the membrane on a flat roof. Often, it is only 2mm to 3mm thick and installations must therefore be carefully planned and checked to ensure the roof surface remains intact.”
The cost of damage
As Fox points out, roof damage can be very costly: “Water ingress into any building will incur the cost of repair to the roof surface. But for some organisations there are also business costs to consider. For example, water damage in a data centre could cost the business billions of pounds in lost data. There are also health and safety issues where water enters occupied space, for example in schools or offices. This could lead to areas of the building being closed off while repair work is carried out.”
Damage can easily be caused by placing air handling units on concrete slabs, or wood blocks. Leaks can often be hidden under the slabs, leading to water ingress to the building. Installers must also be able to work quickly and effectively, without damaging the roof membrane. Big Foot Systems carry a unique independent 15-year warranty for that reason - so that clients know they can rely on our equipment and the installation process not to cause that type of damage.
