Achieving Deep Energy Savings in Existing Buildings through Integrated Design

Commercial buildings consume a large amount of energy - 35% of the nation's electricity, and 13% of the nation's natural gas. And the majority of this existing commercial building stock will still exist over 20 years from now. Such a large stock of existing buildings presents a good opportunity for decreasing our national energy demand through energy retrofits. This paper will present key concepts for cost-effective retrofit projects with deep energy savings (45% and above) in existing buildings. Achieving deep savings typically requires an integrated design process, where all building systems and assemblies are evaluated in a holistic manner. With this process, for example, HVAC equipment replacement measures are evaluated in consideration of load reduction measures. The paper will present examples and considerations related to the integrated design process. The upfront cost of a deep retrofit project may be difficult to justify on the basis of energy savings alone. However, the business case is much easier to make when planned upgrades and equipment replacements are taken into account. The paper will present methods and considerations related to planning for retrofit projects, and evaluating and ranking deep retrofit options. The Department of Energy has recognized the energy savings potential in existing commercial buildings, and has recently published two Advanced Energy Retrofit Guides that target methods for achieving various levels of energy reduction in existing buildings. The guides address the office and retail building sectors. As representative examples of content included in each of the guides, the paper will include technical details from the guides related to specific energy reduction measures. The general project planning considerations presented in the guides are applicable nationwide, while the energy and cost savings estimates for recommended energy efficiency measures have been developed based on energy simulations and cost estimates tailored to five distinct climate zones. The results of these analyses are presented for individual retrofit measures, as well as a package of recommended measures for three project types: operations and maintenance measures implemented through the existing building commissioning process, standard retrofits, and deep retrofits. The paper will present these measures and packages, to show examples of retrofits that can be implemented in existing commercial buildings to achieve various levels of cost-effective energy reduction.