The target in this study was to decrease the energy use for transportation of air (fanenergy) with a factor of three. Two real systems composed of existing componentswere constructed in a laboratory; a mechanical exhaust system and a balanced system.The flow rates through the systems were set at values according to the Dutch BuildingRegulations. This situation is called the reference situation. A number ofimprovements have been tested and studied.
Kakegawa City Hall, completed in March 1996, contains a sixstorey high glass-walled atrium integrated into the open-plan main office areas via stepped terraces. To save energy while still providing a comfortable indoor environment, the type of HVAC system adopted required careful consideration. Frost prevention fans normally used for tea plantations were installed on the terraces to blow warm air downwards during the heating season. Transferring air from the ventilation windows in the office spaces to those in the upper parts of the atrium also achieved effective natural ventilation.
Human thermal comfort in warm conditions can often be improved inexpensively by increased air movement. Two automatic ceiling fan systems are described that regulate air speed to maintain comfort in changing conditions. One system is based on the ASHRAE comfort standard and the other uses the PMV comfort model. In comfort tests at 29°C and 50% RH both automatic systems provided the same level of comfort at steady state conditions as manual control. However the automatic systems were faster in bringing the subjects to comfort.
The wind and buoyancy pressure driving forces for natural ventilation of buildings are very low, typically less than 10 Pa. Depending upon the prevailing climatic and thermal conditions, or even the location of a building on a site in relation to other surrounding buildings and landscape, the predominant pressure force incident on a purpose-provided natural ventilation opening can either be closer to the lower range of pressure differentials (< 2 Pa) or vary over a wider range of higher pressures (2 - 10 Pa).
ASHRAE has long been in the business of ventilation, but most of the focus of that effort has been in the area of commercial and institutional buildings. Residential ventilation traditionally was not a major concern because it was felt that between operable windows and envelope leakage, people were getting enough air. In the quarter of a century since the first oil shock, houses have become much more energy efficient. At the same time, the kinds of materials and functions in houses were changing in character in response to people's needs.
A patented, low energy, fresh air fan convector has been developed by a HVAC equipmentmanufacturer in conjunction with a leading controls supplier and a local University. It canheat, free cool, provide minimum ventilation air and carry out night cooling strategies in anintelligent self contained package. A number of full-scale tests have been carried out on theunit.