Building Energy Resilience

Lighting controls in commercial building have undergone a transformation in the last few years. The simple wall switch (or no switch!) has given way to occupancy sensors and vacancy sensors with passive infrared (PIR) and ultrasonic motion detection. Additionally, photocell sensors have been added for daylighting control. The intent of these advances in lighting controls is to ensure that interior light fixtures are only on when occupants are in a space and natural light levels are inadequate. In my view, we still have a long way to go to achieve this intent across the building design and construction industries.

Throughout the commissioning process, we often find issues with accessibility to equipment, whether it be a heat pump above a ceiling grid or an air handler in a mechanical room. Accessibility to all aspects of a unit is frequently overlooked during the design and construction process. Having adequate clearance is important for the building owner and the maintenance faculty.

HVAC control sequences of operation have a direct impact on the effectiveness and efficiency of building systems. When specified and programmed correctly, control sequences of operation enable HVAC systems to efficiently meet the loads placed upon them. When designed and implemented incorrectly, sequences of operation can cause HVAC systems to either fail to meet building loads or waste energy (e.g. a system trying to simultaneously heat and cool the same space). In order for HVAC systems to operate at their peak efficiency, the control sequences of operation need to be appropriate for both the equipment type and the application.

Introduction

We receive dozens, probably closer to a hundred commissioning requests for proposals (RFPs) every year. The quality, content and requirements are as varied as one might expect. Jennifer Chiodo posted some thoughts on how one can identify quality commissioning services and I’d like to take this opportunity to suggest how one might develop an RFP for commissioning services.

Introduction

In my last post I cited three examples of incomplete or incorrect control programming that all would have had negative effects on building operations or equipment life expectancy. In this post, I want to focus on one piece of equipment, a rooftop ERU (energy recovery unit) and, more specifically, on the graphic page for that ERU. This is another prime example of the controls not being done even though the contractor had said they were complete.

Most people familiar with commissioning recognize the quality assurance benefits of the commissioning process. Building design and construction projects are inherently complex and there are numerous opportunities for errors and omissions. Commissioning brings the benefit of an expert review to the design documents and installed systems. By identifying design and construction issues for the owner and project team, a commissioning agent helps to improve the overall quality of a building project.

We often write about retrocommissioning of existing buildings in this blog and the benefits to the building owners. To put this in context, I thought I would highlight a recent success story. The following project was the retrocommissioning of an existing four-story 100-year-old building. The building houses retail space on the bottom floor and office space on the upper floors. The measures were driven by comfort issues, control issues and an astute building owner who acted on the utility’s audit of opportunities. After two months of monitoring, this HVAC system’s consumption is showing savings of 80% and payback of the project is approximately 2.5 years. Here are the key elements of this retrocommissioning project.

Hotels can potentially use very large amounts of energy because of the 24/7 occupied schedule for common areas and the necessity to have local controls in each guestroom. Typically, these controls are not monitored and not adjustable unless manually changed at the room thermostat.

Building controls are always the last thing to get done on a project – at least on the mechanical side. They basically have to be. You can’t control what isn’t there and until the systems and equipment have been fully installed, started and balanced, the controls contractor can’t finish. As a result, controls contractors are often rushed and expected to complete, say, two weeks of work in two days. The result is often less-than-complete controls or a system that hasn’t been fully vetted which, sooner or later, results in a confused or unhappy building owner or occupants.

In Part 1 of this blog post series, I discussed the process and reasoning behind why it is important to do functional performance testing (FPT) on your building HVAC system. I also provided examples of issues that can arise during this testing, which are typically easily fixed via the DDC (direct digital control) system programming but would have slipped under the radar otherwise. Another reason this testing is performed is to find opportunities for energy savings. Part of our role as energy specialists is to understand how to tailor HVAC systems to provide the same performance while lowering the energy involved to make it work, ultimately allowing your system equipment and components to have a longer life span.