Benefits of Improving the Building Envelope
John L. Pierson, P.E.
Posted: November 13, 2020 | Project Management
Although significant energy savings can be realized through reroofing and exterior renovation projects, a high performance building envelope can provide dramatic improvement to efficiencies in overall building performance. An energy-efficient building envelope can provide remarkable improvements in indoor environmental health and overall longevity of a facility; so when considering an energy improvement project, the building envelope should be addressed first.
An Opportunity for Improvement
Buildings more than 30 years old usually have the best opportunity for making significant improvements when related to energy. Typically, by this time, the envelope has aged through its design life and is in need of repair. Building additions, change of use, and lack of maintenance often result in premature failure of an enclosure and its terminations and transitions. The small air leaks in wall transitions, water leaks in the roof, failed sealants at windows and doors, etc., all contribute to a significant loss in energy. Buildings over 30 years old also tend to have far less insulation in the roof and walls than what is recommended for today’s facilities.
However, newer structures can also suffer from energy inefficiency. While our buildings have become more airtight and better insulated, improper detailing, poor application, or value engineering of whole roof and wall systems have left some owners with poorly performing building envelopes. Whether the building is new or old, improvements to the envelope will not only stop leaks and reduce energy costs, but also create a more comfortable, healthier occupied space at the same time.
Benefits of Improvements to the Building Envelope
While energy conservation measures such as lighting and HVAC control systems typically have the quickest payback, improvements to the building enclosure have energy cost saving benefits that are realized for the life of the building.
Some of these improvements and their benefits include:
• Increasing the insulation in a building to reduce heating and cooling requirements.
• Eliminating large uninsulated thermal bridges to improve heating and occupant comfort.
• Reducing the heat gain of the building through reflective roof membranes, coatings, metal cladding, and glazing. “Cool” materials not only save energy but last longer.
• Increasing the building enclosure’s airtightness to reduce the loss of conditioned air and the potential for damaging condensation. Windows with air leaks not only lose heat, but can lead to moisture damage as well as cold, drafty buildings.
• A highly efficient building envelope reduces mechanical loads to the point where HVAC systems can be upgraded.
• With mechanical loads reduced through higher envelope efficiency, renewable energy systems such as solar PV can be reduced in size and cost as well.
The most significant benefit of a high performance building envelope is the long-term waterproofing and protection to the interior of the building. The costs of interior damages due to building leaks can easily exceed the return on investment from any energy improvements. So, stopping moisture intrusion first ensures the effectiveness of any energy improvements. Additionally, the longer the life of the moisture-control system, the greater the energy benefits.
Take roofing for example. Roofing is accepted as a periodic capital expenditure. What usually happens in between these expenditures is a series of emergency and maintenance costs in the form of fixing leaks and repairing damage. In commercial facilities, the maintenance costs are usually paid out of a separate budget, so they rarely get added to the initial cost for a total life cycle cost of the roof system. The cost of maintaining a roof has a dramatic impact on the benefits of energy improvements: A longer lasting roof, with less maintenance costs, will provide a far better return on investment from the benefits discussed above.
Ultimately, adopting a building envelope strategy that reduces maintenance and repair costs is the best way to improve your return on investment. A leak-free, long-lasting, energy-efficient enclosure is the best way to optimize your energy savings.
Building Envelope Performance
There are several options available today to determine the potential energy savings of building envelope improvements. These energy evaluations provide valuable data that helps determine the economic feasibility of the project. However, these evaluations are often limited to simply adding insulation or a reflective roof surface. There are many other factors that must be addressed when analyzing the energy efficiency of a solution.
Consider the following:
• Additional insulation thickness can complicate waterproofing details at flashings and attachment methods.
• The effective R-Value of an assembly is what counts when considering insulation thickness, so thermal bridging of penetrations and building connections must be considered.
• Air leakage through poor detailing can rob the building of energy — regardless of the amount of insulation installed.
We have the technology and opportunity to renovate our existing buildings to save a great deal of energy. In some cases, the energy costs saved through improvements to the building envelope will pay for a large portion of the project. The benefit is not only financial; performance upgrades to the building envelope can also provide a means for modernizing the appearance, increasing the value of a facility and, most of all, increasing the health and comfort of the space for those who use it.
About the Author: John L. Pierson, P.E., has more than 20 years’ experience in the construction industry and is highly regarded for his thoughtful, creative and efficient approach to building enclosure solutions. In his current role as director of engineering for Garland (https://www.garlandco.com), John supervises a staff of engineers who perform a full range of services to provide high-performance options and solutions to a variety of building envelope projects. John is a frequent presenter of seminars and AIA-accredited classes on building enclosure technology and code compliance.