thermal comfort

The present study investigates the indoor thermal comfort perceived by students through a questionnaire survey conducted during spring 2013 in naturally ventilated primary schools in Athens. Thermal environment parameters such as air temperature, relative humidity, air velocity and mean radiant temperature were simultaneously measured. Then, Fanger’s indices of Predicted Mean Vote (PMV) and Percentage of People Dissatisfied (PPD) were calculated by using clothing and metabolic rates.

This research studies the possibility of introducing combinations of specific mitigation techniques for the urban heat island effect (UHI) in Athens, Greece. A variety of factors, such as surface cover, dense traffic, anthropogenic heat release and urban characteristics including geographic features and climate conditions interact with one another to create UHI, which is becoming increasingly evident also due to the changing climate, which in this region is expected to increase the duration of hot spells and the frequency of heat waves.

The need for more energy efficient Heating Ventilation and Air Conditioning systems led to a search for new systems for heating, cooling and ventilation of buildings. Strong reduction of energy consumption within the built environment is necessary because of the growing effects of depletion of fossil fuel and global warming. This lead to a almost standard concept of energy efficient office buildings in the Netherlands. That concept exists of heat pumps and  LTES aquifers combined with thermally activated building systems (TABS).

Air movement in an indoor space may be experienced in very different ways. For persons feeling cool, air movement tends to be perceived as draught, whilst when feeling warm air movement may provide a desired cooling effect. In the transition zone it therefore seems difficult to use constant air velocity as a tool for cooling without creating draught problems. One possible way to use air movement as a method to improve thermal comfort, without resultant draught problems, could be to use intermittent air velocity instead of constant velocity.

A good level of thermal insulation and an adequate thermal capacity of the building envelope are essential to achieve good energy performance. Many studies have been conducted about this topic, mostly focused on the reduction of energy losses, peak load control and energy savings. Nevertheless, very few studies were realized addressing both insulation and inertia of the building envelope in a thermal comfort perspective, and taking into account the combined effect of different ventilation strategies.

Common experiences, standards, and laboratory studies show that increased air velocity helps to offset warm sensation due to high environmental temperatures. In warm climate regions the opening of windows and the use of desk or ceiling fans are the most common systems to generate increased airflows to compensate for higher environmental temperatures at the expense of no or relatively low energy consumption.

Public residential buildings in Singapore are designed as naturally ventilated. As climate changes, the indoor thermal comfort becomes critical as it depends greatly on the outdoor weather condition. The Predicted Mean Vote (PMV) model developed for Singapore (Givoni, et al., 2006) which depends on indoor air temperature and air speed is used to predict the indoor thermal comfort.

Previous studies have demonstrated that in summertime increased air velocities can compensate for higher room temperatures to achieve comfortable conditions. In order to increase air movement, windows opening, ceiling or desk fans can be used at the expense of relatively low energy consumption.

Natural ventilation is increasingly considered a promising solution to improve thermal comfort in buildings, including schools. However in order to support its planning and implementation, quantitative analysis on airflow paths and heat-airflow building interactions are needed. This requires an adequate accounting of both internal effects, from building layout and structure, and external forcings from atmospheric factors.

The thermal comfort of the residential building Home for Life is investigated with a particular focus on the strategies used to achieve good thermal comfort, and the role of solar shading and natural ventilation. Home for Life was completed in 2009 as one of six buildings in the Model Home 2020 project. It has very generous daylight conditions, and is designed to be energy neutral with a good indoor environment.