APPENDIX B (continued)
Annual Summary--Infiltration. Using the annual psychrometric
chart, determine the percentage time below 67deg.F (19deg.C). See Figure B-8.
more than 10 percent of the annual hours are less than 67deg.F (19deg.C), then
insulated building capable of holding infiltration to under one air change per
hour is required. This eliminates porous wall constructions such as louvered
walls which cannot be tightly shut. Operable louver windows which can be shut
may be acceptable, but fixed open louvers should be avoided.
The upper limit of the climatic data bin directly below the comfort
zone is 67deg.F (19deg.C). The 10 percent exceedence criterion may seem high,
the coldest periods of the day occur when the occupants are in bed under
blankets. The insulation of blankets extends the comfort zone to lower
temperatures, so the amount of time that discomfort is experienced is
considerably less than 10 percent.
Monthly Summaries--Infiltration. If an infiltration-resistant
envelope is required, then this procedure may be examined using the monthly
psychrometric summaries to determine possible seasonal variations.