VIP

In the past and still often today, building regulations and standards don't reflect the state-of-the art with respect to the performance assessment of buildings in terms of energy use and indoor climate. Because of the field of most of these regulations (transmission losses, energy demand for heating,...) and the typical used components, the assessment procedures were rather simple and not really a reflection of the physical behaviour (e.g. dynamic behaviour of buildings).

If the building envelope is not airtight enough, significant amounts of energy may be lost due to exfiltrating air, or damage to structural elements may occur due to condensation. Air leakage can be avoided by appropriate design and careful construction. Test methods to check the quality of airtightness and to locate the individual leakages are available and are increasingly used.

VIP Indoor Air Pollutants, Part 1 defined major types of indoor air pollutants, their measurement, and concentrations guidelines. This second part of the VIP addresses the sources of pollutants and effective measures to control them or to mitigate their impacts on occupants and building contents. The most effective means to control indoor air pollution is through reduction or elimination of pollution sources. Indoor pollutants originate both within the building and from outside. The first step in controlling the sources of indoor air pollution is to identify them.

A heat recovery unit transfers heat (some units also moisture) from the exhaust air stream over to the supply air stream, thus reducing the heat loss due to ventilation, and reducing the need to condition the cold supply air. Conversely, in hot and humid outdoor conditions, a heat recovery unit can keep heat (some units also moisture) outside, thus reducing air conditioning costs.

The principle of displacement ventilation involves air supply and distribution in a room by upwards displacement, i.e. as direct as possible through-flow in the occupied zone in order to achieve high ventilation efficiency. In addition, air distribution by displacement generally makes it possible to supply a larger quantity of air than for conventional mixing ventilation, which requires concentrated supply at high velocity.

Addressing successful solutions to counterbalance the energy and environmental effects of air conditioning is a strong requirement for the future. Possible solutions involve the use of passive cooling techniques and in particular of heat and solar protection techniques, heat amortisation and heat dissipation techniques. Recent research has shown that night ventilation techniques may contribute highly to improve thermal comfort in free floating and decrease the cooling energy consumption of air conditioned buildings.

Natural ventilation is one of the most effective passive cooling techniques. Because of the serious reduction of the wind speed in the urban environment and the corresponding reduction of the air flow rate, for both single and cross configurations, the cooling load on the buildings inside the canyons is much higher than the one of buildings where wind is not obstructed. Thus, it is very important to consider, other techniques than windows to enhance air flow in urban buildings.

Pollutants found in indoor air are often several times higher than outdoors. Indoor air pollutants cause effects ranging from odor, annoyance, and irritation to illness, cancer, and even death. Since people spend the majority of their time indoors, it is important to recognize and control indoor air pollution. Some indoor air pollutants also adversely affect materials in the building and the building structure itself. The majority of indoor pollution comes from the building itself, its contents, or its occupants and their activities.

The necessity to make waterproof sanitary water ducts or central heating tubing and to make airtight natural gas distribution tubing is of primary importance to both construction professionals and the public. However, the airtightness of ventilation ducts and heating or cooling ducts is subject to less attention.
An assessment campaign, aimed to measure the latter, was conducted within the framework of a European project , and demonstrated that the leakage in air ducts in France and Belgium reached figures up to 20% of the average nominal flow rate.