Deep energy retrofit

A deep energy retrofit is a whole-building analysis and construction process that uses "integrative design" to achieve much larger energy savings than conventional energy retrofits. Deep energy retrofits can be applied to both residential and non-residential (“commercial”) buildings. A deep energy retrofit typically results in savings of 30 percent or more, perhaps spread over several years, and may significantly improve the building value.

The term "deep energy retrofit" is often used interchangeably with "deep green retrofit" and "deep retrofit". A deep green retrofit may have less focus on energy efficiency and may emphasize obtaining certification from a green building rating system, such as LEED. The definition of the term continues to be refined and debated.

Conventional energy retrofits focus on isolated system upgrades (i.e. lighting and HVAC equipment). These retrofits are generally simple and fast, but they often miss opportunity for saving more energy cost-effectively.

Deep energy retrofits achieve much greater energy efficiency by taking a whole-building approach, addressing many systems at once. It is most economical and convenient to take this approach on buildings with overall poor efficiency performance, with multiple systems nearing the end of useful life, and perhaps other reasons.

A deep energy retrofit combines energy efficiency measures such as energy efficient equipment, air sealing, moisture management, controlled ventilation, insulation, and solar control so that dramatic energy savings are achieved alongside optimal building performance.

Durability, good interior air quality and energy efficiency are attained by sound building science practices. In a deep energy retrofit, filling a wall cavity with effective insulation also requires careful consideration of how that wall will dry if moisture does happen to get past its skin. Using very high R-value insulation systems on the exterior of the building enclosure is often one of the hallmarks of a deep energy retrofit. Where exactly the dewpoint will fall in (or out) of those thickened walls—and in what climate zone—becomes crucial. Careful detailing, flashing and air sealing of windows and other building penetrations is also key to a successful deep energy retrofit.

Systems thinking is required for these kinds of retrofits, where highly efficient windows are "tuned" to their orientation, and mechanical systems and heat recovery ventilation units are sized and integrated with how the walls, roof and basement are being air sealed, moisture-managed and insulated.

A Level III energy audit, as defined by ASHRAE, is required in order to complete a commercial building deep energy retrofit. Also known as an investment grade audit, this type of energy audit features analysis of the interactions between efficiency strategies and their life cycle cost. Upon selection and implementation of measures, the energy savings are verified using the International Performance Measurement and Verification Protocol.

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