Building Energy Resilience

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.

Who knows technology?

I should know better than to presume anything when someone is speaking about their “furnace,” because what they most frequently mean is “the thing that makes heat.” I was recently asked about a home heater replacement by a relative who is the chief engineer at a major communications company. His question was, “should I replace my furnace to save energy?” I inquired about the efficiency and he replied 88%, which is pretty good for an oil-fired furnace, so I told them that was probably the best they could do. Then I was asked, “what about our hot water heater?,” which was described as “a tankless type fed off the furnace.” At that point I realized that my friend wasn’t using accurate language and that was causing me to give him bad advice. He in fact has a high-mass oil boiler with an indirect fired hot water tank, and since the boiler is near the end of its useful life, he does have an opportunity to replace it with a higher performance boiler.

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.

In a previous blog post, I discussed our process for constructing a scope of work to perform a campus water consumption analysis. At the time, we knew a minimal amount about the existing metering system. A site visit was conducted to allow us to put our eyes on each meter listed for the campus. After this was completed, we were able to provide helpful information to our client regarding the current water consumption and metering system as well as next steps for reducing their consumption using a greater level of water use monitoring.

Before joining Cx Associates I worked as a sales engineer in western New York, with a specialty in Variable Refrigerant Flow and Ductless Split systems. With the new popularity of these systems across the country there are still many questions facilities managers, engineers, and contractors have regarding their cold weather performance. There are several important aspects of these systems to keep in mind before deciding whether they are right for your facility or project that requires cold weather heating.

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.

I recently had a meeting with one of my favorite long-term clients. We met to discuss some upcoming work, and while there, I poked around in the chiller plant mechanical room to see how things were running. We were involved in design review and commissioning for the new chiller plant, and have been impressed with its efficiency. It’s a water cooled chiller with high efficiency, magnetic bearing compressors and all the bells and whistles. In the past, we’ve metered consistently high performance out of the chiller plant as a whole, saving the client many thousands of dollars per year in electrical savings.

My business partner, Matt Napolitan and I each spent 10 years working at major, international engineering firms. I worked for nationally ranked 11^th Syska Hennessy Group in their San Francisco office and Matt worked for 14^th ranked Buro Happold out of their New York office. We now operate a 10-person engineering consulting firm in Burlington, Vermont. We know both large, big-city engineering and local, Vermont engineering.

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.

When it comes to enjoying the many positive features of an enclosed parking garage, most users will not think about the type of ventilation system in place. But an enclosed parking garage poses an issue with carbon monoxide (CO), a very harmful toxic gas that is created when “fuels burn incompletely – most vehicles have an internal combustion engine where this occurs”[1]. Known as a “silent killer,” CO has no odor or color, but can very quickly poison a person before they even sense anything is wrong. Because of this risk, it’s especially important to make sure there is a proper ventilation system in any enclosed area where there is a potential for formation of CO. In this blog post, I will discuss the pros and cons of two current system designs that are typically used. When an engineer designs a ventilation system for an enclosed garage, they carefully calculate how much CFM is required based on square footage and quantity of operating vehicles. Depending on climate and location, the applicable standard/code for ventilation must be carefully followed to ensure the minimum requirements are met.