MIL-HDBK-1011/2

APPENDIX C (continued)

Section 2:

INTERIOR TEMPERATURES

2.1

Purpose

2.1.1

Internal Gain and Interior Temperature Rise. The ventilation

method and overlay in Appendix B assumes that internal gains from sun, lights,

appliances, and occupants are not high enough to increase the interior

temperature. This is usually an appropriate assumption for residential and

light commercial applications with effective sun control and roof insulation.

If internal gains are likely to be large (as in high-rise office

buildings), then it will be necessary to determine the rise in interior

temperature resulting from these high internal gains. The rise in temperature

will be a function of the rate of internal gains and the rate of heat removal.

The primary route of heat removal for this strategy will be by ventilation,

although conduction through parts of the building envelope may play a role.

2.2

Equations

2.2.1

Temperature Rise. The temperature rise can be estimated based on

the following relationship, which holds when averaged over time:

EQUATION:

heat loss by ventilation = internal heat gain

(26)

or:

EQUATION: (ACH) (Thermal Mass of Air) (Bldg. Vol) (delta T) = Q+internal, (27)

where

ACH = air changes per hour

Thermal Mass of Air = 0.018 Btu/lb/deg.F

Bldg Vol = Building Volume in ft.3-

delta T = temperature difference in deg.F

Q+internal, = Q+occupants, + lights + appliances + solar

Rearranging and restating:

delta T = Q+internal, / (ACH) (0.018) (Bldg Vol)

EQUATION:

(28)

2.2.2

Ventilation Boundary Adjustment. In the ventilation design

procedure in Section 2, the ventilation strategy boundaries are compared to

climate data on the psychrometric summary chart. These boundaries can now be

adjusted to account for the higher temperatures indoors. The boundary can be

moved to lower temperatures to represent the outdoor conditions under which

the hotter interior temperatures lie along the ventilation strategy

boundaries.

The new outdoor T+boundary, = original T+boundary, - delta T

EQUATION:

(29)

Therefore if delta T is subtracted from the T+boundary, at the 0.5

or 1.0 m/sec boundary on the original overlay, the additional percentage of

time

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