Understanding when and where to use a virtual building energy audit vs. an on-site energy audit is a key part of delivering a high return on investment in an energy savings program.
The traditional on-site audit that meets ASHRAE Level II standards or higher is still the best way to determine if a building is operating efficiently. It is an activity that involves going to a building to perform leak tests, infrared imaging, blower door tests and a lot of analysis. Properly executed, an energy audit can identify utility expense savings of 10-50%.
Unfortunately, the traditional on-site audit is slow and can be very costly. While some buildings have the opportunity for significant savings, other buildings may not. For energy professionals managing a portfolio of buildings this forces them to be selective, asking: “Where in my portfolio do I invest to get the best results?” This is where a virtual energy audit system can help.
New technologies have emerged for virtual building energy audits making them more powerful than ever. When used as part of a program that includes traditional on-site energy audits, energy managers can significantly improve the payback on their programs.
5 Steps to World Class Building Portfolio Energy Management
Best in class building portfolio energy management programs have five stages:
- Establish Baseline – In this phase, all the building smart-meter data and meta-data characteristics are gathered for the entire portfolio. Then, a virtual audit assessment is conducted to validate the baseline data and flag and eliminate anomalies. This is an important step. From time-to-time, mistakes are made when entering baseline information. For example, in one case, a client of ours was unaware of errors in their building square footage data. After running the data through our system, alerts were raised. After reviewing the raw data, the client found errors in the reported square footage. These were corrected, and the data was updated before moving on to the analysis.
- Prioritization – Once the baseline for each building is established, it is time to rank order the properties in the portfolio. The prioritization process provides two critical pieces of information for the manager. One, it identifies the properties with the most potential for savings, and two, it models the dollar value of potential changes. This second point is important. A properly conducted on-site building audit that meets or exceeds the ASHRAE Level II standards, is costly. On top of that is the cost of implementing the energy conservation measures. A virtual audit system can be used to determine if the on-site audit is cost-effective. In one case, a quick-serve restaurant chain asked us to evaluate a set of their locations. While the modeled payback on various measures at each location was attractive, it was not high enough to justify on-site audits at all stores. Instead, changes to HVAC scheduling and actions relating to refrigeration units were recommended.
- Physical Audit – At select locations where modeled improvements are noteworthy and require implementation beyond simple operational changes, on-site audits may be commissioned. These events provide much more granular detail and analysis. This more intensive review helps sharply focus the possible action plan for each site.
- Energy Conservation Measures (ECMs) – Once the plan for ECMs is set, the measures are implemented. Some measures are point-in-time while others are behavioral. Point in time measures include changes like HVAC replacement or a lighting retrofit. On a follow up basis, they are easy to identify and evaluate. Behavioral changes include actions like thermostat setpoint setbacks or increased refrigeration unit maintenance. To deliver the expected savings they must be actively managed and measured.
- Measurement and Verification and Continuous Commissioning – To achieve long-term success in any energy management program, follow up measurement and verification is a best practice. This can be done on an event-driven basis or on a continuous basis. For programs with limited resources, a virtual audit system can be used to cost-effectively spot-check and validate the impact of ECMs. It can also be used on for continuous commissioning to evaluate energy efficiency on an ongoing basis. This approach is considered best in class for optimizing the efficiency of a building portfolio.
Virtual building energy audits based on new technology are highly complementary to the traditional on-site building audit and they help focus resources and maximize impact. They provide the portfolio manager with a fast and cost-effective prioritization of a portfolio of buildings. They are a crucial part of any comprehensive energy and sustainability strategy.
Source: energycentral
