Hi all,
how should be the atrium lighting power allowance determined in baseline building? If I understand it correctly according to Table 9.6.1 of Standard 90.1-2010 the LPD for the first 40ft in height is 0.03 W/sqf per ft (height) so if atrium is 40ft high the LPD should be 0.03 W/sqf times 40ft what gives 1.2 W/sqf. In the MEPC it only allows 0.03 W/sqf and there is no adjustments for atrium height. So the question is where the problem is - in my understanding or in the MEPC?
Another question: I need to set the VT (visible transmittance) in baseline. According to 90.1-2010 section C3.5 the VT for fenestration in the base envelope design shall be the VT factor from Table C3.5 times the SHGC criteria as determined in this subsection - for climate 5A it is 1.27 times 0.46 (for vertical fenestration), for skylight the VT is 0.40. Is that correct or the SHGC should be determined according to Tables 5.5-1 to 5.5-8 and VT determined from these SHGC?
Due to different fenestration VT in proposed and baseline it is essential to have different interior lighting full load hours based on radiance calculation due to automatic daylighting control. And question is whether the radiance calculation within propsed building should be used in baseline as well or the baseline should have performed its own radiance calculation? The first case should report identical full load hours, second should report different.
Thanks!
Martin
