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Part 1: First Steps to Retrocommissioning
March 2014 -
If a facility manager is considering retrocommissioning (RCx), what are the first steps s/he should take?
A benchmarking effort should be the beginning of all RCx projects. Benchmarking is one high level indicator that a building is a good RCx candidate. Benchmarking means comparing a buildings annual energy consumption to a database of similar buildings to determine if it using an unjustified high amount of energy. Energy Star Portfolio Manager is a good tool for organizing and tracking energy usage and provides a comparative “scoring” of a building’s EUI from 0 – 100. Once the benchmarking is completed, an “end use breakdown” should be developed. The end use breakdown identifies how much energy is used by each system in the building. This is an important step because it not only helps the owner understand how they use energy, but it also serves as a quality control check for the estimated savings identified. For example if the HVAC system is estimated to use 40% of the total facilities energy consumption, then realistically the savings can only be a portion of this quantity.
The early stages of RCx are primarily an information gathering effort. Once a facility manager has decided to move forward with an RCx investigation, data should be gathered regarding historical energy usage (monthly and hourly data if available) and as-built information of mechanical & lighting systems. Interviews with the facilities operation staff often identify operational issues which should be studied as well as energy reduction opportunities. Owners should contact local electric and gas utilities to determine if they offer technical and financial assistance for RCx and if they can recommend qualified firms to assist with the project.
If a building has an Energy Management System (EMS), its extent and functionality should be evaluated. The EMS is a very helpful tool for the RCx process and if it is working correctly, it is often the focus of the investigation of opportunities which may exist. A well-functioning EMS can increase the cost-effectiveness of the RCx investigation by facilitating identification and evaluation of energy efficiency measures.
Setting up trend logs through the EMS is a critical step in the process. If trend logs can be set up months in advance, the RCx schedule can be shortened as it is important to review system performance during all seasons of operation.
Before getting into the details of the RCx investigation, don’t forget to look at the big picture. Establish the current needs of the building and its occupants in quantitative terms such as occupancy, ventilation requirements, and temperature settings. This information will guide the RCx process towards having a building which is comfortable and efficient.
Answers provided by Paul Banks, Principal, B2Q Associates, Inc.
Ask An Expert: Paul Banks, Retrocommissioning
Part 2: Types of Equipment That Should Be Included in Retrocommissioning
Part 3: Consider Whether Design is Still Sensible During Retrocommissioning
Part 4: How To Gauge Whether Retrocommissioning Was Successful