Building Energy Resilience

Outside air economizers are one of the most cost-effective, common, promising and troubled energy efficiency components you can find on a commercial air handling system. The concept is simple and beautiful – use outside air instead of expensive mechanical cooling when possible. When outside air is at the right temperature and humidity levels, turn off chillers, cooling towers and pumps, and bring in free air. In reality, however, while our firm has commissioned hundreds of outside air economizers (new construction and retrocommissioning projects), more than 50% of them have not functioned properly, causing significant energy penalties to the building operating costs.

Functional Performance Testing (FPT) is the process of putting the Direct Digital Control (DDC) system through its paces by manipulating every possible condition the HVAC controls and equipment will ever experience. FPT is an important part of the building commissioning process. Only by testing how the DDC system controls respond to switching from cooling to heating or economizer mode, occupied to unoccupied mode, satisfied to unsatisfied temperatures, or normal power to emergency power, can the building owner know the system will function properly when the contractors leave and the building is handed over. The tests force you to work through the controls sequence language created by the design engineer in a sequential order. As I gain experience as a commissioning engineer, FPT allows me to better understand the “brains” behind why equipment performs and reacts as it does. To make sure a piece of equipment works as intended and can provide the expected performance is the main reason to functionally test HVAC systems.

Energy efficiency programs and program evaluators are working in a market that is changing at an increasingly rapid rate. As governments and professional and green building organizations increase their focus on how buildings impact climate change and the need to drive the market to adopt efficiency at a higher level, they are fostering market change. Rate-payer funded efficiency programs often align well with these initiatives by providing incentives and technical assistance to support customers who have been motivated through these government and market-based initiatives. But the attribution of savings associated with these projects is complex. One example of this is the new energy benchmarking requirements that are rapidly gaining ground nationwide.

Six months ago, I wrote a blog post that described the mobile applications, or “apps” that Cx Associates’ engineers have been finding useful for fieldwork or for deskside analysis support. These ranged in capability from the simple and relatively nontechnical--such as a PDF reader-- to the more technical--such as air property (psychrometric) calculator tools. In the fast evolving field of mobile applications, six months is a long time--and it’s no surprise that a bunch of new apps have appeared. This blog post supplements the last one, so if you have not read it, its worth checking out as well--the apps presented there are still extensively used by our engineers. (Please note that neither Cx Associates nor its engineers are affiliated or compensated by the app developers reviewed.)

I recently had the pleasure of attending the 7^th Annual Commissioning Summit for the Northeast Chapter of the Building Commissioning Association (BCA). The BCA Summit provided a great opportunity to discuss important topics of building performance with Northeast commissioning agents and building owners.

Modern Building Automation Systems consist of three core conceptual components: information inputs (sensors, switches), controls outputs (actuators, VFD’s, relays), and a brain (controllers and a head-end). Traditionally, copper cabling of different kinds has connected all of these devices together in some manner. Each actuator and sensor may be connected directly back to a central controller, or often through local equipment controllers (such as a heat pump above a drop-ceiling) equipped with controls cards with a network interface. Regardless of the specific wiring scheme, the bottom line is that the building owner becomes the proud owner of a virtual spiderweb of controls cabling. In new construction, cabling can be installed before finished walls and ceilings are in place, so installation is not very disruptive and can be cost effective. For retrofit applications however, running new cabling can be very labor intensive and disruptive to surface finishes (drywall, woodwork), which can be ultimately very expensive.

Today ratepayers in many states are making large investments in energy efficiency. I am a passionate advocate for the need to invest in cost effective improvements to our building infrastructure. However, I am concerned that many efficiency programs are taking short cuts to attain near-term goals that will undermine the market’s ability to generate deeper and more lasting efficiency improvements over time.

As an engineer myself, I was struck recently by fresh evidence of the pervasive challenge of communicating technical information effectively. I attended a building conference where the focus is designing better buildings and one common thread emerged. “Death by PowerPoint” is alive and well in the building and design industry.

While performing a recent functional performance test for a school HVAC system, I discovered something that had gone unnoticed by the contractors and building owner: a motorized damper actuator installed backwards. This damper, one of more than a dozen installed in the building, controls the outdoor air intake for one of the ventilation air handlers. When a discovery like this occurs (and discoveries like this are common in building commissioning), it begs the question: what would the cost impact be if the condition went unnoticed?

The building commissioning design review process provides opportunities to see how HVAC designers apply efficiency to pumping systems. There are outstanding designs and, unfortunately, some not so excellent applications.