Next, the actual annual heating degree days is determined from Worksheet
4 by employing Tact in place of the daytime thermostat setpoint to obtain
the base temperature:
Tb = 65.8deg.F
Referring to the weather table for Norfolk and interpolating between base
temperatures of 65deg.F and 70deg.F, we obtain:
DDact = 3,827
Now the actual annual heat load is calculated from the equation provided
on Worksheet 9. The result is:
Qact = 133.5 x 106 Btu
Then the incremental cooling load is calculated from the final equation on
the worksheet and found to be:
QI = 76.5 x 106 Btu
This is quite a large number and points out the necessity for shading the
solar aperture during the cooling season. Since our system has movable
insulation, the means for providing the required shading is already in
5.3.12 Refining the design. The first refinement one might consider to
the four-plex family housing unit would be to increase the building mass.
This could moss easily be accomplished by employing massive partitioning
walls between the individual sections. The addition of more mass would
increase the DHC and EHC of the unit and lead to a higher utilization
efficiency thereby reducing the auxiliary heat requirements.
Additionally, the increase in utilization efficiency might lead one to
consider reducing the size of the solar apertures. This strategy could
reduce the incremental cooling load thereby improving building comfort and
convenience. Alternately, covers or shading devices could be employed to
reduce QD during the cooling season.
The quantitative effect of any design refinements on building
performance can be determined by entering the change on the appropriate
worksheet and working forward from that point.