Brainstorm and vet ECMs

An important activity during early design, especially during a design charrette, is for the project team to brainstorm and vet energy conservation measures (ECMs). An energy modeler is often expected to lead this activity. This section provides guidance on identifying potential ECMs and some considerations for the vetting process.

Identifying Potential ECMs

Consider the stage of design

The choice of appropriate ECMs to evaluate can vary depending on the stage of design. Pay special attention to identifying ECMs that require early design planning such as daylighting and natural ventilation. Some ECMs, such as high-performance glazing for the windows, may be appropriate to evaluate at later design stages.

Some ECMs may also require different levels of analysis depending on the stage of design. For example, during early stage analysis, a general study of HVAC system alternatives and efficiencies is common. During later stages, the analysis may become more focused on specific features of the system such as fan efficiencies or control strategies.

Look for ECMs covering a range of design features

There are many building systems that affect energy consumption.

• Architecture
• Electric lighting
• Receptacle loads
• Mechanical air-side systems
• Mechanical water-side systems
• Electrical
• Renewable energy

Identify maximum technical potential

A useful exercise is to consider each design feature and identify an option that provides the maximum technically possible performance. The idea is to briefly put aside questions of cost effectiveness or practicality and identify ECMs that would likely provide maximum savings. This exercise can provide several benefits: it might inspire ideas for ECMs that would have otherwise been overlooked, and it helps the project team to understand where there are inefficiencies in the design.

For example, when evaluating windows, include a super insulating option, which could be a triple or quadruple pane window with U-factor as low as 0.15 Btu/(hr-F-ft2). Then combine that window option with opaque constructions that maximize cavity and continuous insulation. When evaluating the results, check for the impact on heating loads; in some cases a super-insulated envelope might allow significant downsizing or even elimination of perimeter heating systems. Perhaps a less expensive type of heating system then becomes feasible.

Find inspiration in case studies and references

There are many references that can serve as a source of ideas when brainstorming ECMs. Some include lists of ECMs, others describe case studies that can serve as examples.

• ASHRAE's Advanced Energy Design Guides and Zero Energy Design Guides cover a range of building types.
• AIA's Architect’s Guide to Building Performance lists potential design questions and describes analysis case studies.
• ASHRAE's Research Project 1651, Development of Maximum Technically Achievable Energy Targets for Commercial Buildings, identified close to 400 ECMs and performed analysis of 30 ECMs.
• The Project Stasio website includes a page with a list of design questions that can be evaluated with BEM.

Review lists of potential ECMs

Check out this page with lists of potential ECMs.

Vetting ECMs

Factors to consider

There are many factors that might be considered when vetting a list of ECMs. The potential energy savings are, of course, a primary consideration, but there are many other potential impacts that can be important to consider, such as:

• CO₂ emissions reduction
• Cost effectiveness
• Impact on HVAC system sizing
• Space requirements
• Thermal comfort impact
• Indoor air quality impact
• Impact on construction schedule
• Availability of equipment or materials
• Maintenance requirements

Design charrette or team meeting

Some of the factors listed above can be evaluated using BEM, but others require different types of analysis or input from project team members with special expertise. That complexity is one reason that a design charrette or other meeting of project team members from different disciplines is a good time to review and vet ECMs. A discussion that includes, for example, the architect, mechanical engineer, electrical engineer and structural engineer can help in identifying integrated impacts of ECMs. An ideal case is that the vetting process uncovers win-win strategies, like when an ECM both saves energy and reduces construction cost.