Conquer Whole Building Energy Efficiency Retrofits in 3 Stages

Call the energy retrofit doctor! Historic and existing buildings may look alright on the outside, but they could be a lot more energy efficient. Don't get me wrong; they have potential. Through the years, these properties have often been updated and remodeled, usually to address particular issues, without considering effects on whole-building energy efficiency. We tend to compartmentalize our homes, and changes to them reflect this paradigm. In the past, we many have needed more space, so we built an addition or enclosed a porch. A room got too hot or cold, so we installed an A/C unit or baseboard heater. You might live in a house with these kinds of alterations.

This kind of thinking allows for quick comfort and cheap solutions (in the short-term) but does improve the property value or allow it run at its best. This approach costs you more in operational energy expenses over the life-cycle of the building. Essentially, when we are relying on a more energy intensive solution to solve our issues, we are not thinking holistically. There is a simple strategy for this kind of holistic thinking. Through the "Whole Building Design" approach, historic and existing buildings can achieve their best performance. 

Photo credit: via / CC BY-SA

Whole Building Design Approach

Whole-building energy retrofits are something that everyone can participate in doing - improving their building’s performance in a scalable, cost-effective manner.  Even more encouraging, retrofitting our already green existing, older homes and Main Street commercial buildings is a sure path toward them becoming more highly valued and the greenest buildings in town. 

Diagram by National Institute of Building Science |

Diagram by National Institute of Building Science |

The Whole Building Design Guide (WBDG) was created for all kinds of buildings and offers a systematic approach to create more efficient, healthier, and smarter buildings. Through partnership with the National Institute of Building Science (NIBS), development of the WBDG is a collaborative effort among federal agencies, private sector companies, non-profit organizations and educational institutions. Its success depends on industry and government experts contributing their knowledge and experience to better serve the building community. 

3 Stage Approach for Building Retrofits

Whole-building energy efficiency retrofits can reduce operating costs and improve property value. They may also improve interior comfort and assist in work productivity. Knowing where to begin can be a challenge, though, since energy use, mechanical systems, occupant behavior and the exterior envelope are interdependent of each other.

For an existing building, a whole building retrofit for energy efficiency should follow a simple 3-staged approach. They are the following:

  • STAGE 1:  Improve Operations
  • STAGE 2:  Reduce Energy Loads
  • STAGE 3:  Upgrade Systems

Below, I will outline this approach based on a resource created through the Oklahoma Main Street Program. It is in the form of a 20"x30" poster, entitled "Historic Building Energy Efficiency Guide". You may download this resource to print and enjoy. This work would not have been possible without support from the Oklahoma Main Street Center, Main Street America, the Preservation Green Lab, and funding from Oklahoma Energy Office.  

Poster by Oklahoma Main Street, Oklahoma Department of Commerce

For either historic or other existing buildings, this resource outlines a straightforward approach for a proper whole-building energy efficiency retrofit. Below, the "Retrofit Process" section of the poster has been adapted and expanded.

    STAGE 1:  Improve Operations 

    Inspect, Conserve & Maintain

    A. Both regular system inspections or a comprehensive building energy audit (aka home energy assessment) will take a closer look at major building systems, user behavior and the building envelope. Some utility companies offer something similar to an level 1 energy audit and seasonal tune-ups at a low-cost, or even free. For a more extensive energy audit, you will need to hire an energy efficiency professional, or consult with an architect with energy experience. 

    B. Use Energy Star Portfolio Manager to understand your baseline energy usage, and track your efficiency gains, through the whole building retrofit process. Portfolio Manager tracks your utility bills, so you can analyze retrofit effectiveness directly.

    C. Get to know more about the construction era of your home and the systems installed.  Ask a professional which vulnerabilities of your building’s energy performance you can most effectively address.

    D. Occupant behavior has a large impact on your energy profile. Adopting power saving strategies that mitigate your building’s weaknesses will provide the largest return for investment (ROI). 

    E. Routine, proactive maintenance of your building’s systems can ensure that they are operating at optimal efficiency while also preserving their lifespan. 

    STAGE 2:  Reduce Energy Loads

    Local Utility Incentives

    Major utility providers provide extensive incentive programs to small business owners  and home owners for upgraded or replaced equipment. By working either directly with the customer or through a trade ally, the utilities offer money for energy efficient lighting, HVAC, plug loads, and even just using less energy during peak times. These incentives decrease the initial costs of installing energy efficient equipment and lead to quicker paybacks.


    Reducing energy loads through lighting is often a key step. Newer LED lighting options require far less energy and emit less radiant heat (to cool) in process. By adding room sensors and task lighting, you can further this reduction. 


    Add Advanced Power Strips to shut off power to equipment and electronics.  By setting electronics (such as computers) to ‘sleep mode’ after 15 minutes can cut unnecessary power drain and reduce excess heat produced by idle devices, saving on cooling costs.

    Photo credit:  eflon  via  /  CC BY

    Photo credit: eflon via / CC BY


    Consider envelope upgrades that are congruent with your building’s historic character. Repair and retrofit major elements (such as windows) instead of replacing them and keep them operable instead of sealing shut. Although envelope improvements can be costly, they have the greatest potential to add both comfort and curb-appeal to your property. Consult an architect with historic preservation experience.

    STAGE 3:  Upgrade Systems


    With reduced energy and heat loads you may be ready to downsize and upgrade your HVAC equipment and ductwork. Automating your HVAC with a programmable thermostat, or building automation system (BAS) - to reflect the active use of your building - can immediately save energy and preserve the life of your equipment. Adjusting temperature set points as low as possible will help maximize your return on investment. 

    A programmable thermostat is a good way to begin lowering energy costs today. I like the wi-fi enabled versions with 7-day programmable capability - in case you forgot to turn down the heat on the way out to work. Essentially, you can enact your own version of your electrical company's "smart hours" in style. Set some of the time zones to pre-cool your home before the rate hike begins. In Oklahoma City, peak hours are from 2-7pm.

    Note:  While writing, I will periodically share helpful “affiliate links” of materials that I find truly valuable. If you purchase these products (or anything else) from Amazon in the window that opens from the link, I receive a small commission in return. This is at no cost to you, but helps me keep the blog running. 


    After assessing the demand for hot water, you may be ready to reduce excess storage. Optimizing the delivery system is also key to saving energy.

    Action Steps

    After reading, you should also refer to the bottom section of the poster for distinct retrofit options. From left to right the column colors coordinate with the 3-stage retrofit flow chart (at right). In each column, the retrofits are ordered from top to bottom, ranging from no-cost/low cost retrofits, to moderate cost, to investment level retrofit options. There is ongoing research to better quantify the potential ranges for each retrofit.

    If you work through the stages from top to bottom - respecting feasibility and constraints - you should be able to maximize energy savings. In your path to implementing a whole-building energy efficiency retrofit, it is alright if it takes a little time to complete the options that you select. Each retrofit saves energy, and over time your energy savings will grow.  

     You should now have a grasp on:

    • The best approach for reduce energy usage in existing and historic buildings.
    • The most cost effective energy efficiency retrofits.
    • How to maximize return on investment (ROI) for energy efficiency retrofits.

    As mentioned, the research is ongoing toward maximizing whole-building energy efficiency retrofits. I would love to hear any questions, feedback or ideas.

    Thank you for reading!


    Additional Resources: 

    Energy Savers: Tips on Saving Money and Energy at Home

    Weatherizing and Improving the Energy Efficiency of Historic Buildings

    Illustrated Guidelines on Sustainability for Rehabilitating Historic Buildings

    Saving Energy in Historic Buildings: Balancing Efficiency and Value

    Small- and Medium-Size Building Automation