Air conditioning would not be required as often in a HTM building as temperature remains more constant - however if required, air-conditioning could be called upon.
The Criteria for Selecting a System for the Block
You should ensure rooms such as those containing numerous computers have sufficient ventilation and air conditioning as this not only helps improve the performance of the computers but also makes the environment more comfortable as heat is a waste product given off by them.
Other considerations are solar gain from windows and density of people in the room. I would advise a number of windows allowing natural light through rather than one large pane as less solar gain will be a consequence. Large surface areas of glass may look appealing but can cause intense heating. It may also be an idea to implement an air conditioning system in a hall where an assembly may take place, or a lecture theatre, which becomes densely populated in a short period of time. These kinds of spaces can also be empty for long periods.
Ideally we should ensure that all new property is properly procured through the use of Whole Life Costing (WLC) studies to help best value solutions and select specifications that reflect costs to the college and make use of properly planned maintenance regimes. Running costs should also be taken into consideration.
Air conditioning systems have developed over the years and no longer create excessive noise. Ideally the system would be silent – but a noise level of 35 db would be acceptable, as this is the acceptable level for a library as stated in ‘Environmental Science in Building’.
The Fire Risks that are associated With Ventilation and Air Conditioning Systems
Oxygen is necessary for a fire to ignite. Ventilation and air conditioning systems facilitate the introduction of fresh air containing oxygen which feeds fire. If a fire starts it is necessary to control the flow of air to prevent the fire being fed and to prevent the fire from moving along ventilation ducts.
Materials used in the air conditioning system should be fire retardant; there should be no contamination of flammable materials which may have entered the system such as waste material during construction. Otherwise fire could spread from the source to potentially anywhere in the building; heat and smoke on their own could set off fresh fires; therefore, they must be prevented from circulating.
Fire dampeners are built into the ductwork and automatically close in the event of a fire - triggered by heat or smoke. This compartmentalises the building, at least in terms of ventilation. Fire doors also serve to prevent the spread of fire; they automatically close after they have been opened. They should complete compartmentalisation, trapping the fire in one area.
Smoke extractors remove smoke and hot gases which could potentially build up and ignite, and ease the effects of smoke on occupants of the building. The smoke discharged allows fire fighters to pinpoint the location of the fire, especially in a large building.
The Integration of the Ventilation and Air Conditioning Installations with the Other Services
Light fittings should be kept to a minimum to reduce the amount of heat given off by artificial light. Natural light is therefore going to be essential in reducing this by introduction through windows and roof lights. The orientation of the building would be advantageous if it were south facing as only surfaces facing south receive sun all year round. Occupancy sensors which activate the lights when required would enhance the efficiency and reduce the waste heat given off by artificial lighting, reducing the need for air conditioning / ventilation.
Windows that can be opened (which is not always the case) allow the occupants to control their own environment and maintain a comfortable temperature and level of ventilation.
Heating could be provided by a variety of means, for example, electric heaters. Heat could be provided via the hot water system; or it could be provided via the air conditioning system. In an integrated building design as much heat as possible would be extracted from the hot water system to provide maximum energy efficiency lowering reliance on air conditioning or other heating efforts. If the air conditioning system was used as the primary heating system, emphasis would be placed on energy efficiency and the use of heat exchangers to retain as much heat generated as possible in the building as air passes outside. In the case of the Elizabeth Fry building at the UEA, 85% of heat was retained in 1995 (although this subsequently dropped to 80%), showing the potential for energy conservation.
A Building Management System (BMS) is a system of computer control and analysis for building functions, which monitors and can automatically react to circumstances. For example, the heating system could be set to activate when the temperature drops below a certain level. The capability of the BMS depends on the level of automation of a building: in some buildings even windows are computer controlled. Connecting telecoms systems to the BMS allows for greater flexibility in managing the system, which can then be managed off-site by a central operator from his PC.
How the Best Performance of the Services Installations can be assured
During and after construction the building should be checked for departures from and problems with the specification. Mistakes may have been made: for example, temperature sensors were placed near ventilation inlets rather than outlets, which meant that the internal temperature could not be adjusted in a timely manner. This occurred at the Elizabeth Fry building at the UEA. Flaws may also become apparent – things don’t always go to plan.
Mechanical systems promise automated, efficient control of buildings’ functions. They may work perfectly, or, more likely, is prone to teething troubles and glitches which could require maintenance or even re-evaluation and replacement: this sometimes results in a computerised system that fails to work acceptably being abandoned for the traditional manual method. In many cases initial problems will be worked through as those using and operating the building get used to the new system, which can lead to improvements in efficiency over time. Automated systems can also use stored data to improve on the effectiveness of their originally programmed routines over time.
Complex control systems will need to be adaptable to changed conditions – if the building was used by twice as many people as planned for, the heating and cooling systems would need to be reset to cope. The weather could divert from its usual pattern – there could be a warm winter. In some establishments, the boilers are switched on in November and left on regardless of pertaining weather conditions. A greater degree of flexibility is required.
The Implications of the Construction Design and Management (CDM) Regulations with Regard to the Services to the Building
The burden of regulation is heavy and extensive, falling on the construction and components of the building, the systems working inside it and the people who occupy it. It also provides a framework for safety and security.
Prior to construction starting a planning supervisor prepares a pre-tender stage health and safety plan. Before work starts on site, a principal contractor is also required to develop a safety plan; the differences in the coordination and management of the safety plans are: pre-contract - the health and safety during the design stages, and post-contract - health and safety during construction.
Care must be taken installing heavy equipment such as boiler plant – once it is in place the only problem should be maintenance.
COSHH – Control of Substances Hazardous to Health – is very important. Formerly, dangerous materials such as asbestos were used with abandon. Now, the risks are more apparent and toxic substances are generally avoided in building materials. However, the use of dangerous chemicals may still be required, such as solvents, during construction. The operation of the building can require the storage of hazardous materials used in cleaning, cooling systems, and fire prevention systems. The benefits outweigh the dangers, which are managed by restricting access, servicing the systems to prevent failure, and educating staff in the use of hazardous materials, safety equipment and reaction to accidents.
Proper maintenance is necessary for all aspects of the building, but especially failure-critical components such as ladders and guard rails which would pose a grave danger if they failed. Wiring also requires extensive checking and maintenance to negate the risk of electric shock.
The safety of users in their ability to access things is important – for example, whether someone has to overstretch to reach a fuse box or switch. When using equipment (such as computers, switches, or taps, or touching pipes) they should be safe from electric shock, heat, or scalding water.
The air-conditioning and ventilation system should be designed and maintained to prevent breeding conditions for diseases such as legionella. An outbreak of Legionnaire’s Disease could result in a conviction for manslaughter. Lesser diseases, mites, dust and fungi, can also be spread through ventilation and cause SBS. Of course, they should also be designed to be fire-safe, as outlined previously, as should the rest of the building, which should have fire doors, smoke alarms, sprinklers, extinguishers and clearly marked escape routes.
Bibliography
Books
McMullan, R. (2002) Environmental Science in Building, Fifth Edition. Hampshire: Palgrave Macmillan
Everett, A. (1994) Mitchell’s Materials, 5th Edition. Essex: Longman Group UK Limited
Greeno, R. (2000) Building Services, Technology and Design. Essex: Pearson Education Limited.
McMullan, R. (2002) Environmental Science in Building, Fifth Edition. Hampshire: Palgrave Macmillan
Websites
Health and Safety Executive Website – () (Online) (Accessed 20th May 2005)