Engineering

The building envelope consists of everything that keeps the indoors separated from the outdoors and controls the flow of water, air, and thermal energy between those spaces. The envelope is the most expensive component of most new building projects and generally the most expensive to repair when it fails.

There are three opportunity points to impact the quality of building envelopes: in the design process, during construction, and through maintenance or repairs. The City of Madison invests in its buildings for the long term, so the decisions made at these points can have financial and operational ramifications for the next 50 years and longer.

In the design process, Facilities staff reviews the design documents to ensure that the building envelope will conform to best practices for durability and energy performance.

During construction, Facilities staff coordinates with the design and construction team, and makes frequent site visits to verify that the envelope components are being installed properly.

On certain construction projects, the City of Madison utilizes blower door testing to establish the air tightness of the building envelope.  Before the building‘s envelope is completed, a blower fan is sealed into a door opening and used to pressurize the building. The rate of pressure loss determines how “leaky” a building is.  A smoke stick may be used to identify sources of air leakage so they can be addressed.

Efforts during design and construction can prevent and greatly minimize building envelope failures, but the need for maintenance to keep a building envelope functioning properly is ongoing over the life of the building. Roofs and sealant joints are routinely monitored and replaced on a scheduled basis. Facilities also works with various agency operations staff to investigate and address individual building envelope problems as they arise.