Friday, October 13, 2006

Combining the High-Performance Building Alternative

Note page 25 excerpted from Washington State ELCCA Guidelines, which documents the acceptable criteria for using one of the previously-studied alternatives as the High-Performance Building (HPB) alternative.

According to the criteria, the HPB alternative may use ANY previously studied alternative, PROVIDED that it meets the energy savings goal of the LEED scorecard. IF the previously studied alternative will meet the energy goal only with a some modification (e.g. the addition of heat recovery and/or demand ventilation) THEN the MODIFIED ALTERNATIVE may be used as the HPB. However a modified alternative is still another alternative, and so must be analyzed equivalent to the others.

Note that the HPB alternative does not necessarily need to be based on the 'Renewable' alternative. But 'waste heat recovery' can qualify many of the systems we design as renewable alternatives (see Table 4.3 the ELCCA Guidelines, at the top of page 25), and this feature will help significantly in attaining the LEED energy goal.

So what is the 'energy goal' referred to by LEED as the benchmark criteria?

The energy goal is defined per ASHRAE 90.1-2004 Appendix G as the energy savings required of the HPB over the Baseline Building (BLB):

LEED 2.1 EAc1:

1 Point New Buildings 10.5% Existing Buildings & Renovations 3.5%
2 Points New Buildings 14% Existing Buildings & Renovations 7%
3 Points New Buildings 17.5% Existing Buildings & Renovations 10.5%
4 Points New Buildings 21% Existing Buildings & Renovations 14%
5 Points New Buildings 24.5% Existing Buildings & Renovations 17.5%
6 Points New Buildings 28% Existing Buildings & Renovations 21%
7 Points New Buildings 31.5% Existing Buildings & Renovations 24.5%
8 Points New Buildings 35% Existing Buildings & Renovations 28%
9 Points New Buildings 38.5% Existing Buildings & Renovations 31.5%
10 Points New Buildings 42% Existing Buildings & Renovations 35%

Attaining LEED Silver requires 33-38 points on the LEED Scorecard; the ELCCA Guidelines further stipulate that no less than four points shall be earned from the 'Energy Optimization' portion of the scorecard for the HPB alternative.

So, the bottom line is that the HPB alternative is required to show improved savings of 21% for new construction, and 14% for existing buildings and renovations over the BLB.

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