Forum discussion
CS-2009 EAp2: Minimum Energy Performance
Dear community,
According to tables 5.5-1 (climate 1a), the Solar Hear Gain Coefficient for the proposed building should be no more than 0.25. Is this a requirement for the proposed building?
I was wondering if there's a possibility to trade off some SHGC (i.e. allow a bigger SHGC) with other design options - such as reduced glazing areas for example?
Your help will be greatly appreciated.
many thanks
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Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
June 7, 2013 - 12:26 pm
The SHGC is not a mandatory provision and is therefore not required for the proposed. SHGC can be traded (you can exceed the prescriptive value as long as you achieve enough savings in other areas). It cannot be traded for window area as this must be identical in both models (unless the proposed exceeds 40% window to wall then the baseline is 40% and the proposed is as designed).
Ioannis Rizos
Environmental ConsultantChapmanBDSP
June 10, 2013 - 4:33 am
Marcus, many thanks for your input.
I was also wondering if there's flexibility in the R values for the roof assembly/insulation level? Table 5.5.1 appears to limit the resistance of the roof assembly to a Uvalue of 0.19 W/m2K (SI system) - and a Rvalue of 5.3 m2K/W (SI) for insulation alone. Can the proposed building have less insulation than what table 5.5.1 suggests?
Many thanks in advance.
Ioannis
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
June 10, 2013 - 8:39 am
Yes. All of the prescriptive values in the 5.5-X tables are available for tradeoff.