Retrofit Manager’s Industry Briefings team explains the role of building envelopes in retrofit projects and their contibution to energy efficiency, indoor comfort and building durability.
An RM Practice Briefing on the importance of building envelopes in building retrofits, and their impact
Building envelopes, consisting of the walls, roofs, windows, and doors of a building, play a crucial role in the energy performance and comfort of a building. Functioning as a barrier between the interior and exterior environments, they help regulate heat transfer, moisture, and air infiltration. Within the context of building retrofits, which involve upgrading existing buildings to improve their performance, building envelopes are a critical component that must be considered carefully to ensure successful project outcomes.
Energy Efficiency: Reducing Heat Transfer and Air Leakage
Building envelopes are instrumental in reducing heat transfer between the interior and exterior of a building. Insulated walls, roofs, windows, and doors can significantly reduce heat loss during the winter and heat gain during the summer, leading to lower energy consumption for heating and cooling. According to the U.S. Department of Energy, buildings are responsible for approximately 40% of the total energy consumption in the United States, and improving the energy efficiency of building envelopes can have a significant impact on reducing this energy consumption, lowering utility bills, and decreasing greenhouse gas emissions (U.S. Department of Energy, 2021).
Building envelopes are the first line of defense in controlling energy use in buildings. By minimizing heat transfer and air leakage, they play a crucial role in reducing energy consumption and greenhouse gas emissions.
(U.S. Department of Energy)
In addition to reducing heat transfer, building envelopes also play a vital role in minimizing air leakage. Air infiltration, or the uncontrolled exchange of air between the interior and exterior of a building, can lead to energy waste, discomfort, and indoor air quality issues.
A properly designed and sealed building envelope can help prevent air leakage, improving the energy performance of the building and ensuring a comfortable and healthy indoor environment. This is especially important in retrofit projects, where older buildings may have gaps, cracks, and other air leakage pathways that need to be addressed to achieve optimal energy efficiency.
A well-designed and sealed building envelope is crucial for minimizing air leakage, improving energy performance, and ensuring a comfortable and healthy indoor environment.”
(Building Performance Institute, Inc.)
Indoor Comfort: Enhancing Thermal Comfort and Indoor Air Quality
Building envelopes also have a significant impact on indoor comfort. A well-insulated and properly sealed building envelope can help maintain consistent indoor temperatures, reducing temperature fluctuations and drafts that can lead to discomfort for occupants. This is especially critical in retrofit projects, where older buildings may have inadequate insulation and air sealing, resulting in uneven indoor temperatures and discomfort.
Furthermore, building envelopes play a crucial role in improving indoor air quality (IAQ). Proper insulation and air sealing can help prevent the infiltration of outdoor pollutants, such as dust, pollen, and outdoor air pollution, into buildings at a time of wider public awareness about the impacts of indoor air pollution on health and well-being following the Covid-19 pandemic.
Building envelopes are essential for maintaining thermal comfort and indoor air quality in buildings, ensuring a healthy and comfortable environment for occupants.
(Green Building Council Australia)
Building Durability: Protecting Against Moisture and Mould
Building envelopes also play a critical role in protecting buildings against moisture intrusion and mold growth. Moisture infiltration through the building envelope can cause structural damage, decay, and mold growth, leading to costly repairs, health issues for occupants, and reduced building durability. Proper insulation, air sealing, and moisture management strategies, such as vapor barriers and drainage systems, are essential to prevent moisture intrusion and protect the building envelope from damage
CASE STUDY
Empire State Building Retrofit, New York City
- The retrofit of the Empire State Building was motivated by the building ownership’s desire to:
1) Prove or disprove the economic viability of whole-building energy
efficiency retrofits.
2) Create a replicable model for whole-building retrofits.
3) Reduce greenhouse gas emissions. - the project included replacement of windows, insulation and air sealing.
- Results of the retrofit including a 38% reduction in energy consumption and significant cost savings.
- “The retrofit of the Empire State Building’s building envelope resulted in significant energy savings, improved comfort for occupants, and reduced greenhouse gas emissions.” – Johnson Controls
CASE STUDY
The Tower at PNC Plaza in Pittsburgh
- The retrofit project, including the installation of double-skin facades, green roofs, and energy-efficient glazing.
- Results of the retrofit, including a 50% reduction in energy consumption and LEED Platinum certification.
- “The retrofit of the building envelope at the Tower at PNC Plaza resulted in a significant reduction in energy consumption and a high level of sustainability certification.” – PNC
//issuu.com/burohappold/docs/bh-pnc-tower-case-study-_pageturnin
References
- Energy Star. (2017). Building Envelope. Retrieved from //www.energystar.gov/campaign/seal_insulate/building_envelope
- U.S. Department of Energy. (2020). Building Envelope. Retrieved from //www.energy.gov/energysaver/design/building-envelope
