PR2009

The dependence of the ventilation on the indoor particulate pollution is highlighted by numerousstudies. The aim of the present study is to examine the influence of the ventilation on the levels of theparticulate concentrations found in dining halls where a large number of students are accommodated. Indoor particulate sources were also quantified.Measurements were conducted in four University dining halls, which are located in different parts ofthe city of Athens.

It is well known that appropriate ventilation represents one of the prerequisites for achieving goodindoor comfort, and we try to ensure a continuous and sufficient intake of fresh air into a building. But,ventilation losses are also one of the most important components of a building thermal balance, andwe try to reduce them as much as possible. In theory, these two seemingly contradictive facts can betechnically adequately solved in various ways.

A questionnaire presented to designers demonstrates the difficulty to explain the specific status, thestratification and the correlation of parameters, features, concepts, principles and requirements.

Renovation of existing buildings, in order to reduce energy consumption, represents a big market inEurope. As the first efforts often concentrate in improving insulation and airtightness of the buildingenvelope, important insufficiencies of ventilation can appear, generating health risks for the occupants and a degradation of the frame. Taking into account the difficulties to insert ductworks in existing buildings, it can be easier to use distributed ventilation systems for room-by-room ventilation instead of centralised systems.

On the way to the solution of our energy-problems, the conditioning of buildings is the most importantsector. We have to create new buildings, that produce more energy than they need in the course of ayear, so called plus-energy buildings and we have to perform large-scale retrofitting of existing buildings. Priority must be given to increasing energy-efficiency. Having fulfilled this, the implementation of renewable energy has to be undertaken.

One of the topics studied in the European IEE-ASIEPI project (www.asiepi.eu) is the way envelopeairtightness is dealt with in the EPB-regulations of the Member States. To this end, a number of surveyshave been made among the participating countries. Also a quantitative comparison on a samplebuilding has been performed. The results of this study are used in the development of an instrumentto compare the energy performance requirement levels among the Member States.

Thermal bridges increase the building energy demand for heating and cooling. For well insulatedenvelopes and buildings with increased energy efficiency, the influence of thermal bridging on theenergy consumption is of major importance. Here the ratio between the thermal bridging effect and the overall thermal losses increases compared to low or medium insulated buildings and it is possible that the effect of thermal bridges on the energy demand compensates or even overtakes, for instance, the energy gain provided by thermal solar collectors for domestic hot water.

Since 1991 has Sweden regulations on compulsory inspection of ventilation systems (OVK). Thereasons to issue these regulations were many studies on poor indoor climate and health problems for building occupants. The studies have shown also that poor upkeep and maintenance have led to a decline in the performance of existing ventilation systems. If, in the future, we do not look after ourventilation systems properly and adapt operation and maintenance to current user habits, then evenmore buildings will become problem buildings.

In 2005 the first Energy Efficiency Plan for South Africa was developed by the Department of Mineralsand Energy. This plan sets the target for energy efficiency improvements of 12% until 2015. Onepoint of the strategy is to improve the energy performance of public buildings like schools. Manyschool buildings in South Africa are inadequate to provide a suitable learning and teachingenvironment for students.

The influence of ventilation on the energy performance of a building is generally considered to be quite high. It rises clearly, when a building contains large-volume spaces. A famous example building for that is the Reichstag building in Berlin, housing the German parliament. The huge plenary hall in the buildings centre, which occupies only 4% of the total net floor area but 20% of its net volume, is equipped with a powerful air-conditioning system.