MIL-HDBK-1011/2
APPENDIX B (continued)
STEP 5:
DETERMINING NEED FOR HEATING EQUIPMENT
5.1
Annual Summary--Heating. Using the annual psychrometric chart,
determine the percentage of time below 61deg.F (16deg.C). See Figure B-9. If
more
than 10 percent of the annual hours are less than 61deg.F, auxiliary heating
will
be required. In addition, the building envelope must be capable of holding
infiltration to less than 0.5 air changes per hour, which eliminates jalousie
windows and other openings which cannot be tightly shut.
The 60deg.F value corresponds to the upper limit of the bin below a
typical balance point of a free-floating residential building with roof and
wall insulation and air exchanges restricted to 0.5 ACH.
5.2
Monthly Summaries--Heating. Repeat the same procedure to determine
seasonal requirements for heating using the monthly psychrometric charts. If
heating is required for more than 25 percent of the time during the month,
then the natural cooling strategy will not be applicable and the auxiliary
heating system will be used during that month.
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