Building Energy Resilience

Retrocommissioning (RCx) is a great way for facilities owners and managers to improve energy efficiency and performance of existing building systems without incurring large capital costs. Some projects result in such great savings that simple payback can be less than a year. The RCx process involves assessing the operating performance of existing equipment in a facility, and then making recommendations to improve the performance based on the results of the assessment. These improvements are typically done by making adjustments to how the equipment is controlled.

The number one barrier to retrocommissioning is the upfront cost of the engineering study. In general, building owners cannot easily determine the potential value of such studies or understand the quality and content that is necessary to support an energy efficiency investment. This makes many customers reluctant to invest $20,000-$70,000 in an engineering study.

As a company that does a good amount of retrocommissioning (RCx) – the commissioning process applied to existing buildings – when taking on a new project we are often faced by a question asked by both ourselves and our clients: “Where do we start?”

Part of a marketing stumbling block in our commissioning field is the lack of quantifiable benefits to our work. People understand commissioning will enable their systems to work more smoothly, generating less maintenance issues and longer equipment life. People understand that commissioning will benefit their building with more comfort for their tenants and finer temperature and humidity control for their processes. But quantifying any energy reduction attributed to commissioning is usually not in the project’s budget and is all too often forgotten when everyone moves on to new projects.

Have you ever wondered how utilities and energy agencies run energy efficiency programs for installing recommended products such as variable frequency drives and LED lighting? Evaluation, Measurement and Verification (EM&V) is a crucial part of evaluating energy efficiency programs. EM&V provides an assessment of how well the program is performing. This goes beyond assessing the performance of the installed energy efficient measures; it also provides an assessment of how customers perceive and use the program. EM&V makes energy programs sustainable by providing feedback through multiple and diverse sources of information.

I take climate change very seriously and do what I can in my personal life and through my career in energy efficient building commissioning to mitigate my impact on the environment. But I am also cautious of doomsayers who call for unrealistic achievements or all is lost. So I was motivated to do some investigating recently when I read that the Intergovernmental Panel on Climate Change states that “global emissions need to hit zero by 2100 to keep global warming below 2°C by the turn of the century.” That struck me as such an idealistic goal. Can we really do that? I decided I wanted to educate myself and, of course, found that this iceberg is deeper than I expected, and the answer is not simple. In this post I’d like to share its complexity and, in a subsequent post, I will speak to my interpretation of realistic goals.

Replacement Chiller Needed – But What’s the Cooling Load?

We were hired recently by a commercial customer to work on the replacement of a ~120 ton chiller plant dating back to at least the 1980s. When we were brought on board, the plan was to install a 165 ton chiller to replace the existing unit. The facility had no building management system (DDC) and therefore the owner didn’t have the ability to accurately assess the building’s actual cooling load. In our experience, many customers in our area who do not have process loads actually have had cooling loads come down over the past 20 years. This trend is likely due to reduced lighting waste heat resulting from lighting efficiency upgrades and improved windows (low-e). We decided it may be a good idea to meter the plant to determine actual loads before sizing the new chiller plant.

Healthcare operating rooms (ORs) are one of the most critical types of indoor environments. That means OR designers and operators tend to pay a high level of attention to OR HVAC (heating, ventilating, and air conditioning) systems. However, many OR designers and users overlook opportunities to operate OR HVAC systems more efficiently.

The least utilized part of the building commissioning process is the act of going back to a completed project and proving the monetary value of the commissioning work. This is an added cost but is very important for the building owner as well as the commissioning agent to ensure changes were implemented correctly. Fortunately, we have many affordable options these days to measure the energy consumption of our building equipment before and after our commissioning work. Armed with this real-life performance data, we can present the owner with hard evidence of the value of fine-tuning a building’s mechanical system. We recently did such a review of two buildings which underwent building commissioning in the past 18 months. By analyzing the data, we found savings for these buildings range from 18-30% with relatively short payback periods.

Let’s be honest with ourselves: when it comes to estimating the potential energy savings of proposed energy efficiency/conservation measures (EEMs/ECMs), there is uncertainty. Assumptions and uncontrolled variables can make or break the preliminary estimates for an EEM/ECM. For example, a $5,000 lighting controls EEM/ECM may offer annual energy savings of $1,000/year (5 year simple payback) if a facility is unoccupied for 4,000 hours per year, or only $750/year (7.5 year simple payback) if the same facility is unoccupied for only 3,000 hours per year. Unknown and uncontrolled variables, such as building occupancy and use, introduce considerable uncertainty to estimates of energy savings.