If you are earning two points at 14%, the first round of the model should aim for a minimum 16%–17% cost savings. There may be reduction with changing design or modeling mechanism. Also remember the energy cost savings typically involve the building systems and assume 25% process loads fixed between design and baseline.
Option 1 energy simulation often requires hiring an energy-modeling consultant, adding a cost (although this ranges, it is typically on the order of $0.10–$0.50/ft2 in North America, depending on the complexity). However, these fees produce high value in terms of design and decision-making assistance, and especially for complex or larger projects can be well worth the investment.
Option 1 energy simulation provides monthly and annual operating energy use and cost breakdowns. You can complete multiple iterations, refining energy-efficiency strategies each time. Payback periods can be quickly computed for efficiency strategies using their additional first costs. A building’s life is assumed to be 60 years. A payback period of five years is considered a very good choice, and 10 years is typically considered reasonable.
If your project combines new construction and existing building renovation then whatever portion contains more than 50% of the floor area would determine the energy thresholds.
Hotels, multifamily residential, and unconventional commercial buildings may not be eligible for either Option 2 or Option 3, because the prescriptive guidance of these paths was not intended for them. Complex projects, unconventional building types, off-grid projects, or those with high energy-reduction goals are better off pursuing Option 1, which provides the opportunity to explore more flexible and innovative efficiency strategies and to trade off high-energy uses for lower ones.
Option 3: Prescriptive Compliance Path: Advanced Buildings Core Performance Guide is another, more basic prescriptive path. It’s a good option if your project is smaller than 100,000 ft2, cannot pursue Option 2 (because there is not an ASHRAE guide for the building type), is not a healthcare facility, lab, or warehouse—or you would rather not commit to the energy modeling required for Option 1. Your project can be of any other building type (such as office or retail).
Complying with Option 2 earns 4 points, and with Option 3, 2-5 points and Option 4, 1 point. If you are committed to greatly reducing energy usage and earning a higher number of points, then follow Option 1 for compliance with both EAp2 and EAc1.
Option 2: Prescriptive Compliance Path: ASHRAE Advanced Energy Design Guide for Small Office Buildings 2004 refers to design guides published by ASHRAE for office projects of 20,000 ft2 of less. These guides outline strategies to reduce energy use by 30% from ASHRAE 90.1-2001 levels, or an amount equivalent to a 10%–14% reduction from the ASHRAE 90.1-2004 standard. If you choose this compliance path, become familiar with the list of prescriptive requirements and commit to meeting them.
Option 1: Whole Building Energy Simulation offers the most points, but it requires estimating the energy use of the whole building over a calendar year, using methodology established by ASHRAE 90.1-2004, Appendix G. Option 1 establishes a computer model of the building’s architectural design and all mechanical, electrical, domestic hot water, plug load, and other energy-consuming systems and devices. The model incorporates the occupancy load and a schedule representing projected usage in order to predict energy use.
