El aspecto normativo: la categoría Actividad preventiva

Any good IAQ starts at the structure’s design stage. When designing new builds or when retrofitting buildings, the pollution that the building’s activities is expected to generate must be considered. Other consideration is the pollution neighbouring buildings generate. For buildings designed to take advantage of natural ventilation, adequate openable windows should be provided for the spaces. For buildings that are not designed to be ventilated using natural ventilation, adequate mechanical ventilation system (e.g. ACMV) powerful enough to suck out contaminated air from the building spaces should be added in the design, whilst the HVAC pumps in clean fresh air into the building. The HVAC system must be placed (in the design) on the side of the building that is expected to have the best outside air quality. According to the IEE (1996) the design must take into consideration; the position of the building, the exhaust opening position, traffic routes, car parks, unloading bays, refuse chutes and other nearby ground level or close to evaporation cooling towers.

During design, deciding on what ventilation systems to use – whether natural ventilation or mechanical ventilation depends on the use of the building and pollution load envisaged. Natural ventilated buildings have opening or envelopes in which air, driven by natural forces, enters the building and exits through other openings. Here, the building and its openings are part of the ventilation system and the ventilation system’s design has to be integrated in the building design from the early stages of design (EC, 2003). On the other hand, in mechanically ventilated buildings, the building itself is not part of the ventilation system but its design would nevertheless incorporate aspects where the HVAC system will be installed. According to the EC, “in mechanically ventilated buildings the ventilation air is conditioned

before it is supplied to the rooms via the duct system. Because of supply and exhaust air fans the system is more flexible in respect of building design, and more energy efficient if heat recovery is used.”

The design of the air conditioning and mechanical ventilation (ACMV) system should be adequate enough with regards to the building size, spaces, and activities that will take place within the building, so that the spread of contaminants in the building are kept to the lowest possible level (IEE, 1996). The ACMV system itself must not be made of materials that emit toxic chemicals into the supply air, harbour bacteria, or generate fungi that are harmful to occupants. Adequate frequent cleaning of the system should also be done. In addition, at the

design stage, the proposed building materials and finishing must not be chemical emitting, fungi or bacteria generating. The building materials must be fit for purpose and must not compromise good IAQ objectives. Furthermore, value-engineering process must not be an exercise where good IAQ is sacrificed for low cost materials. Good IAQ must be top in the priority list. The building design must make doors and windows and spaces accessible and cleaning possible.

Electrical works e.g. fittings, wirings, conduits, etc. should be made with non-chemical emitting coats and materials that can be harmful to occupants. Also mechanical designs: water supply, drainage, boilers, sewerage and other installations should be well planned for construction and installation in such a way that the risk of leaks and consequential damage caused by leaks is prevented (IEE, 1996).

Furthermore, during design and construction, there should be an IAQ manager, someone responsible for making sure that design, construction and commissioning goes well to provide the best IAQ possible for the building. Achieving good IAQ should be done in an integrated team, where all partners to the project from the design to the construction process, are included in decision-making. The European Commission emphasize that “IAQ in buildings is affected by several partners in the construction process. The final result depends particularly on the architectural and mechanical designs… Main contractor, mechanical contractor and several subcontractors also affect the final result… In this complex process it

would be beneficial to appoint a person who is responsible for the IAQ in the process.”

The rise in indoor air quality (IAQ) problems has been attributed to the prevalent use of the traditional approach to achieving IAQ, which is illustrated in Figure 2.17. When IAQ is bad, building owners and managers can find themselves devoting considerable resources to resolving occupant complaints or dealing with extended periods of building closure, major repair costs, and expensive legal actions. Despite these significant impacts, IAQ is still not a high-priority in design or building management as compared to function, cost, space, aesthetics, and other attributes such as location and parking (ASHRAE, 2009). It is important to make IAQ part of the design at the very beginning of the project. The primary reasons are: to avoid problems that occur when IAQ is treated as an afterthought; and to allow for alternative design concepts that involve decisions made early in the design process (ASHRAE, 2009). Providing technical and evaluated solutions and their effective usage are the keys to efficiently improve IAQ. Incorporating IAQ at the very beginning of conceptual design gets a number of key issues before the design team, enabling them to make informed decisions that will affect the project through the construction and occupancy phases (ASHRAE, 2009).

“Many IAQ problems are the result of IAQ not being considered as a key issue at the very beginning of the design process. Basic design decisions related to site selection, building orientation, and location of outdoor air intakes and decisions on how the building will be heated, cooled, and ventilated are of critical importance to providing good IAQ. Efforts to achieve high levels of building performance without diligent considerations of IAQ at the beginning of the design process often lead to IAQ problems and represent missed opportunities to ensure good IAQ. Lack”

Figure 2.18: Integrated Approach of achieving IAQ (ASHRAE, 2009)

The beginning of the design must adopt an integrated approach to achieving good IAQ. The easiest and most effective way to accomplish integrated design is to assemble the entire design team at the beginning of the project and to brainstorm siting, overall building configuration, ventilation, thermal control, and illumination concepts as a group. The give- and-take of the initial design charette with the key members present will help each team member to appreciate the specialized concerns of the others and enable the group to develop a solution that best integrates everyone’s best ideas (ASHRAE, 2009). Figure 2.19 shows the construction activities that facilitate achievement of good IAQ.

Figure 2.19: Construction Activities to facilitate good IAQ (Source, ASHRAE, 2009)