Methodology for the Evaluation of Natural Ventilation in ... - Cham

Chapter 1.0IntroductionEnergy consumption and building performance are key issues when evaluating the life cycle ofcommercial office buildings. As energy costs increase, there is a desire by owners, operators, anddesigners to reduce energy consumption and operating costs in commercial office buildingswithout impairing indoor air quality. Beginning with the energy crisis in 1973 attempts weremade to make buildings more energy efficient, resulting in increased insulation levels and moretightly constructed buildings (Allard 2002). Subsequent building construction practices led tomoisture entrainment issues, causing mold that negatively affected the health of occupants.After a series of problems with Sick Building Syndrome (SBS), building construction strategieswere revised, and in the mid-1990s natural ventilation and low energy building design began todevelop as an alternative approach, through innovative heating, cooling, and ventilation methods.In a study of office buildings in California comparing naturally ventilated buildings andmechanically ventilated and air-conditioned buildings, it was found that naturally ventilatedbuildings had the least number of health issues when compared to mechanically ventilated andair-conditioned ones overall (Fisk et al 1993, Seppanen and Fisk 2002). Certain buildingcharacteristics have emerged from the study of low energy and passive cooling designs as themeans to ensure good building performance. However, problems have surfaced as well,including difficulties with the integration of building components, cooperation betweenengineers and architects, and having to develop new techniques for evaluating these passive andlow energy designs.Current aspects of low energy building design include lighting and controls, ventilation systems,and the improved building envelope. Lighting energy can be reduced through the use of highefficiency fixtures and controls such as occupancy sensors that turn banks of lights off when nomovement is sensed, and photosensors that reduce the light output as needed to maintain aminimum light level. These technologies combined with design details like light shelves, highwindows, external shading and atria, increase the natural daylight throughout the building whilereducing energy consumption associated with artificial light. Systems that consume energyrequired for providing fresh air to meet indoor air quality requirements can be reduced oreliminated with the use of passive or hybrid technologies. Hybrid ventilation, or the use ofnatural and mechanical systems to cool and ventilate buildings, offer opportunities to takeadvantage of the external conditions when appropriate, but have a mechanical system to maintainthe indoor environment when the external conditions are not adequate. Additionally, buildingenvelope systems such as high levels of insulation or the use of thermal mass can help to temperthe internal environment, reducing the amount of supplementary heating or cooling needed tomaintain occupant comfort.In addition to overall building performance, the indoor environment and occupant comfort hasemerged as an important design consideration in both mechanically and naturally ventilatedbuildings. Passively cooled and ventilated buildings have many benefits not only in reduced15