Question 6.2: Estimate the heating and cooling degree-days for the base te...

Based on the weather data of Appendix C, available at the CRC Web site www.CRCpress.com/product/isbn/9781439828717 the average temperature and standard deviation in Denver for the month of May are, respectively, T_{o,m} = 57.2°F and σ_{yr} = 8.7°F.

For heating degree-days, Eq. (6.33) is used and provides Z_{m} = 0.321. From normal distribution tables, f(Z_{m}) = 0.379 and F(Z_{m}) = 0.626. Then, Eq. (6.32) gives:

DD_{H}(T_{b})=σ_{m}.N_{m}.[Z_{m}F(Z_{m}) +f(Z_{m})]             (6.32)

Z_{m}=\frac{T_{o,m}-T_{b}}{σ_{m}}       (6.35)

DD_{H}(T_{b})=(8.70).(31).[(0.321)(0.626) +0.379)]=156.5°F-days

Similarly, for cooling degree-days, Eq. (6.35) is used and provides Z_{m} =–0.321. From normal distribution tables, f(Z_{m}) = 0.379 and F(Z_{m}) = 0.374. Then, Eq.(6.32) gives:

Z_{m}=\frac{T_{b} T_{o,m}}{σ_{m}}       (6.333)

DD_{H}(T_{b})=(8.70).(31).[(0.321)(0.374) +0.379)]=69.7°F-days