Energy Analysis for Preservation Projects: The Right Tools at the Right Times

by Dana Kose

July 28, 2017

Using the right energy modeling tools at the right time in the design process is important to the design of buildings. This is especially true for historic preservation projects where modeling can be used to ensure the highest performance of systems when preserving, rehabilitating, restoring, modernizing, or adaptively using culturally significant buildings.

The design industry can take cues on this concept from the auto industry where a variety of model types are used to test and improve the viability of new products. Appropriate specialized models test specific outcomes: for example, a visual model (meant to show matters of color, detectable details, textures, etc.) would not be used to simulate vehicle aerodynamics. Similarly, it is important that design teams working on a historic preservation project use the right tools at the right time.

Traditionally, the design community has relied on “rules of thumb” in lieu of performance modeling. Though not guaranteed to be optimal, these rules, based on past experience, were perceived to be good enough for most projects. However, not all thumbs are created equal, especially in historic preservation where many projects are unique. What worked for one historic preservation project may not be the right solution for the next one.

The rule of thumb is one tool among countless more that we need to make sure we’re using at the right time. Different types of models may be needed to answer different questions during different phases of the design or life of a historic building.

There are three primary types of energy models that can be used in the building lifecycle:

  1. Models for design decisions
  2. Models for design/certification
  3. Models for building operation

In design, if you are not measuring how close you are to your energy goal, you don’t know how far you have to go to get there. Models for design decisions are comparative in nature and allow design teams to understand which energy saving strategies provide the best value. For instance, is it more valuable to add wall and/or roof insulation or update to LED lighting? Integrating these types of energy models early in the design process can yield substantial life-long building energy savings, while maintaining or enhancing the cultural significance of historic structures, without significantly impacting the project budget.

Models for design/certification entail documenting compliance with an energy code or a building rating system. These models, typically completed after construction documentation is finished, measure the expected energy performance of the preservation project upon completion.

In building operation, if you are not measuring how close you are to your energy target, you don’t know how far you have strayed from it. Models for building operations are used to: compare how the building actually performs as compared with the model for design; to determine why there may be a difference; and finally, to make operational adjustments to get the building performance back on track. There are many reasons why a historic building may not perform as expected including differences in weather, building operation hours, plug load assumptions and more.

There are many tools within each of these energy model types. When deciding which tool is most appropriate for historic preservation, it’s important to ask questions such as:

  • How early in design do you want to have results?
  • How detailed do you want the energy model to be?
  • How fast do you want the results?
  • Do you have a unique and/or complicated building type?

With answers to these questions, you can engage an energy modeling professional to deliver results with the right tool at the right time so your project team can make informed decisions about both the design and operation of historic preservation projects.