Building Energy Resilience

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.

With the hot, humid weather behind us, it’s time to review the status of our HVAC systems and ensure they are prepared to operate efficiently in the shoulder season and winter months.

Air source heat pumps have been around for a long time. Especially in climates more moderate than the northeastern United States, they have been the primary space conditioning equipment for a large fraction of homes. Relatively recent developments in high efficiency air-source heat pump technology have pushed heat pumps into colder climate zones such as the northeast US, and have pushed the technology into different end uses. Over the past several years, water-source heat pumps for domestic hot water heating applications have entered the marketplace in the US. Five years ago, heat pump water heaters (HPWH) were difficult to find; now, most major water heater brands have a heat pump water heater option.

I recently had the opportunity to familiarize myself with the Energy Star Portfolio Manager system, which is a free online tool to track and analyze a building’s energy usage via benchmarking. Benchmarking has been previously blogged about by Ben Fowler and Jennifer Chiodo. Certain property types (e.g., hospital, medical office building, office building, etc.) are eligible for an Energy Star score when you have at least 12 months of utility data.

You might have noticed that data analytics (i.e., “Big Data”) have been getting a lot of attention lately in the media. “Big Data” is now a common topic of discussion in media outlets covering business and technology ventures. “Big Data” generally refers to the work of corporations like Google and IBM that use large digital data sets of consumer or civil activities to reveal meaningful patterns and relationships that may be exploited. The recent growth of data analytics as a business venture is an outgrowth of increasing amounts and types of digital data, such as Internet search data, cell phone location data, and utility “smart meter” power consumption data. Smart meters now provide the unprecedented capability to collect and analyze real-time electric power consumption data across much of the electric grid. Right now there is considerable interest around using smart meters and data analytics to gain insight into energy efficiency opportunities in residential and commercial buildings.

I’ve been working in the energy efficiency arena since I started designing buildings under California’s brand new energy code in the early 1980s. I’ve worked in most sectors of the industry from projects to programs, implementation to evaluation and policy. During my tenure financing has been a rising cry as a means to move the market. While I agree that financing is a critical tool in the belt of energy service providers, it is not a panacea and in fact, too much focus on financing as a solution without a clear understanding of the systemic barriers to energy efficiency may result in broken programs that don’t meet goals.

In one of Cx Associates’ latest blog posts, Energy Metering Devices: What’s New, Katie Mason describes data loggers (aka energy metering devices) used in the industry to diagnose building system issues and calculate energy consumption. This data collection technology has come of age in that the loggers themselves are not outrageously expensive and modeling software has developed into a strong analysis tool. For a building owner, this means data loggers can clearly diagnose where equipment is operating poorly, triggering increased energy and maintenance costs. Data loggers are also instrumental to managers of local, state or regional energy efficiency programs in order to accurately calculate energy savings attributable to efficiency improvements. Let's look in more detail at these two applications of the new energy metering technologies.

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.