Performance Based Rating and Energy Performance Benchmarking for Commercial Buildings in India

Abstract

Performance based rating systems serve as an excellent baseline “report card”. They are useful for evaluating performance of existing buildings and to set meaningful targets for new buildings. It replaces guesswork with a scientific methodology to establish targets, evaluate performance and reward innovations. Over time, it helps to consistently improve the standards through healthy competition by shifting markets to better performing levels. In the US, LEED for Existing Buildings (LEED EB), ASHRAE’s BuildingEQ and the Green Globes Existing Buildings rating system reference actual building performance benchmarked against ENERGY STAR Target Finder. On similar lines, this research could help improve current rating systems in India by providing contextual benchmarks and targets across building types. A database of existing buildings with record of their physical, operational and location characteristics and energy consumption and related parameters is a prerequisite for any performance based ratings. USA has been collecting such data in form of the Commercial Building Energy Consumption Survey (CBECS) for many years and has used it to develop ENERGY STAR and green building rating systems. This paper uses the first national level initiative in India to collect and rigorously analyze standardized energy use data for 760 commercial buildings. We use regression and distribution based methods to compute energy consumption benchmarks and at a performance based ratings for India. Specifically, this study (a) Elucidates the need for benchmarking and performance based rating in the Indian context, (b) Discusses the framework for national level data collection, (c) Performs exploratory analysis of whole building energy use across different groups such as use types, climate, operating hours, size, etc. (d) Proposes a methodology for performance rating and benchmarking using regression and distribution analysis, (e) Establishes performance benchmarks and rating scales for building types, namely – offices, hospitals and hotels, and (f) Concludes with limitations and extensions for further work in the Indian context. INTRODUCTION The Indian building sector has witnessed huge interest in the field of energy performance in the last decade. The national Energy Conservation Building Code (ECBC) and green building rating systems such as Leadership in Energy and Environment Design (LEED-India) and Green Rating for Integrated Habitat Assessment (GRIHA) have further fueled this surge in interest. These codes and rating systems are based on design intent rather than actual performance during building occupancy. They are not designed primarily to rate energy performance of existing buildings and to reward their performance through a systematic evaluation and award scheme. Further, they do not provide defendable energy consumption targets for new buildings based on contextual data. T his has serious performance, market and policy implications. Buildings, along with other consumers must continuously monitor and improve their performance in order to transit to an energy efficient economy. It is important to measure this performance against established benchmarks. The primary aim of this initiative is to improve the design, construction, maintenance and operation of buildings by measuring energy performance against established benchmarks, and recognize and reward exemplary performing buildings through a credible certification system (Hicks and Von Neida, 2005). CONTEXT Commercial buildings in India account for nearly 8% of the total electricity supplied by utilities. Electricity use in this sector has been growing at about 11-12% annually, which is much faster than the average electricity growth rate of about 5-6% in the economy (Bureau of Energy Efficiency). According to the 17th Electrical Power Survey of the Central Electricity Authority, electricity demand is likely to increase by approximately 40% in 2011-12 and 175% in 2021-22 2 as compared to 2006-07. The share of electricity use in the building sector has increased from 14% in the 1970s to nearly 33% in 2004-05. In spite of the fast-paced growth of the commercial building sector in India, energy consumption data for the sector is largely unavailable in the public domain. Absence of macro-level data has been a barrier for the government to formulate effective, market-oriented policies and for the private sector to invest sufficient resources to make the buildings more energy-efficient. The creation of these benchmarks will help in identifying exemplary buildings as well as poorly performing buildings. The former can provide clues to designing and operating efficient buildings while the latter can be excellent targets for implementing energy efficiency measures. In some cases, benchmarking can replace energy audits that have been largely ineffective in turning potential into reality. With this in mind, the Bureau of Energy Efficiency (BEE), with technical assistance from USAID ECO-III project, embarked on an initiative to provide sector-specific energy consumption data and undertook the preliminary benchmarking initiative. With inputs from the BEE’s technical committee members, the ECO-III team designed a standardized format for collection of building energy data. The data collection process began in December 2008.