Strategic retrofit investment from the portfolio to the building scale: a framework for identification and evaluation of potential retrofits

摘要

Buildings account for approximately 40% of the total energy consumption and associated GHG emissions globally. Within this sector, approximately 80% of buildings in North America are more than 15 years old and in the intervening years, energy codes have been revised to require 25% less energy than buildings meeting 2000 codes. As a result, even sustainably-rated buildings over 10 years old tend to compare poorly with new buildings built to minimum code standards. Significant investment is required to bring the performance of these buildings in line with market expectations and competition for newer, more sustainable buildings. In large portfolios, the challenge is not only to identify the optimal building retrofits, but also which buildings have the most improvement potential. This paper presents a three step approach to overcome this challenge. First, the building portfolio is screened from the often limited available data and potential energy improvement potential and commercial improvement potential are ranked to identify priority buildings. Second, a series of retrofit bundles is tested on the priority buildings to calculate estimated energy savings, required capital and resultant op erating costs and qualitative indicators affecting occupant comfort to prepare a financial analysis. These estimates are refined using an energy model for the most promising retrofit bundle. Finally, portfolio- wide strategies are developed for the non-priority buildings to take advantage of 'low hanging fruit'. Four global case studies using this framework are presented, two at the portfolio scale and two at the building scale. In each case, the evaluation tools and techniques, modeling approaches and data used in this decision-making are described and resulting project recommendations are presented. Although developed primarily for commercial buildings, this approach is applicable to all buildingtypes and recommendations are offed for its adaptation across sectors.