Previous blog posts from my colleagues and I contain a detailed explanation of functional performance testing (FPT), an overview of how functional performance tests are created, and specific examples of how conducting FPT contributes to better building performance and energy savings. In this post I would like to expand upon the previous post “Functional Performance Testing Done Right: Details Matter.”
As I discussed in a previous post, “Optimizing Air Handling Units for Energy Savings or Improved Comfort,” energy savings can be realized by adjusting the amount of outside air that is introduced to an air handling unit during normal operation. In that article I referenced ASHRAE 62.1 to determine what the correct amount of outside air an air handling unit should mix with the return air stream. This same principle applies to air handlers in healthcare, and in many cases, there is an even greater opportunity for savings in healthcare applications.
As a follow up to my previous blog post on peak shaving, this week I’m going to cover demand limiting. This is another peak shaving strategy that we are also using on the project I mentioned in my last post. Demand limiting is different than energy storage in that instead of using the same amount of energy from different sources than the grid to peak-shave, the amount of energy being used is limited to achieve the same peak shaving goal. I would like to note that there is no reason these two strategies can’t be used together - we are actually using both strategies on a current project to achieve the customer’s peak shaving goals.
Topics: Energy Efficiency
On a current project that Cx Associates is consulting on, the client has a goal of reducing their building’s peak demand charge. For commercial customers, peak demand charges are usually charged based on the peak kW demand of the building or facility during a certain time (e.g. 1-4 PM) of the day. If there is a peak kW outside of this specific time frame, there is no “peak demand charge” from the utility for this peak kW.
Metering equipment, such as light loggers, temperature loggers, and AC current loggers can be very useful tools and sometimes necessary in the world of energy efficiency consulting. They can provide useful data on how equipment is operating and performing. I have written about metering in previous blog posts including one called “EM&V Metering: Right Place, Right Time, Right Duration” where I described the importance of identifying the correct way of deploying meters. In this post I am going to discuss the importance of verifying that meters or loggers are working correctly even before a metering plan is developed or the devices are deployed, as well as the importance of ensuring that the correct sensors are chosen for the application.
On a recent project at a large hospital Cx Associates examined the feasibility of consolidating two air handlers into one single air handler. One of the air handlers is nearing the end of its useful life, and is the reason this project was brought to Cx Associates. While making an in-kind replacement was looked at, the replacement of this air handler presented an opportunity to replace another that was also aging, and located in a position that would be difficult to replace in the future. By combining the two air handlers into a single air handler there was an opportunity to essentially upgrade two air handlers at once at a lower cost than replacing them individually at different times. Maintenance advantages can also be realized by reducing the number of air handlers to maintain in the facility by one.
In commercial buildings all air handlers, whether they are mass produced roof top units or custom built indoor units, are built and installed with an outside air intake and damper. This outside air intake and damper has a large effect on both the energy use of a building and the indoor environmental quality (IEQ) of a building. When performing retro-commissioning, Cx Associates often finds these outside air dampers are not adjusted properly (or are broken entirely) leading to either high energy use or poor IEQ. By optimizing air handling units, energy savings or improved comfort (or both) can sometimes be achieved.
Building commissioning has become more common on commercial construction projects over the last few years due to the many benefits the commissioning process offers, and in some cases due to new building codes. During this time owners, architects, engineers, contractors, and construction managers have become more familiar with what commissioning is, and how it affects them. However, it seems that it’s still often unclear to project teams exactly how to integrate the commissioning authority (CxA) and commissioning process into the construction process. I believe the first part of the integration begins with communication between the CxA and the rest of the project team. The importance of communication in the commissioning process cannot be overstated.
Topics: Building Cx & Design Review
On a recent project we were tasked with trying to reduce the peak electric demand of a building that already had a relatively low summer peak demand of around 40-45 kW and even lower winter demand of around 25 kW. Immediately ideas jumped into our head that we should look at the four installed rooftop units and the commercial kitchen equipment as sources for peak electric demand savings.
Before we began any analysis though, we metered the feed of nearly every electrical distribution panel in the building to check for any anomalies. We found what was expected – the kitchen and RTUs accounted for a large amount of the electrical demand. However, when we compared this data with the utility meter (total power of the building) data for the same time period we found that one feed we did not meter turned out to be an important one.
Variable Refrigerant Flow (VRF) systems are becoming an increasingly popular HVAC solution for commercial construction projects around the country. They offer many benefits that can be realized by architects, engineers, contractors, and end users. Some of the benefits include energy efficiency, flexible installation, and local controls for end users. I began my career by spending two years as sales rep for a VRF manufacturer, and the following are some observations I made during that time about issues which commonly caused problems during installation.