Refer to Appendix C, Section 2, for information on computer
simulation of building thermal performance.
Method 4. For one-story buildings, field modeling may be
substituted for wind tunnel testing (refer to Appendix C, para. 1.4 for a
description of requirements). The results can be plotted on the bioclimatic
chart or input into a computer program to determine comfort levels.
Method 5. A thermophysiological model may be used to determine the
percentage of time that the building will be comfortable, based on a
computer-generated hourly simulation of human thermal comfort. Predictions of
the interior air velocity rates (determined by one of the methods listed
above), and hourly indoor thermal conditions (from computer thermal analysis)
are required as input. For important or complex buildings, this method will
provide the most accurate estimate of thermal comfort. Refer to Appendix C,
para. 3.1 for a description and procedure.
Introduction. Natural ventilation is commonly combined with
seasonally adjustable buildings.
Zoned Buildings. The zoning approach combines natural ventilation
(or other passive cooling strategies) and HVAC systems spatially within the
building. In one form, zoning involves migration of occupants by providing a
variety of thermal zones, each of which is comfortable under a different set
of climatic conditions. Because each thermal zone is tuned to a limited set
exploit a particular site characteristic such as orientation or placement near
water, a particular material characteristic such as thermal capacity, a
particular climate characteristic such as nighttime downslope winds, or a
particular cultural or social pattern such as sleeping outdoors. Traditional
examples of such zones are the verandas/porches of the southern U.S. and the
rooftop sleeping areas of Middle Eastern buildings.
Seasonally Adjustable Buildings. These are suitable for variable
climates in which natural ventilation applies for only part of the year.
Seasonally adjustable buildings aim at balancing the differing requirements of
the various seasons. The characteristics of the building envelope and siting
will vary depending upon the length and severity of the seasons. They
commonly employ seasonally adjustable features such as storm windows,
insulated shutters, and solar shading devices such as awnings and vegetated
trellises. Refer to para. 188.8.131.52 for information on solar control.
Requirements and Recommendations. Perform the Climate Analysis in
Appendix B to determine the percentage of time that natural ventilation will
provide comfort and the air velocity required to achieve comfort in the given
climate. This method also examines possible seasonal variations which may
affect the building design.
Early Stages of Design. The designer should consider zoned or
seasonally adjustable envelope configurations during the early stages of
design in order to maximize their effectiveness.