Energy code advancements for power systems
Over the last 10 years, dedicated energy codes have been supplementing standard building codes, with lighting systems and controls dominating code sections related to building electrical systems. Energy losses and occupant consumption of power system components in commercial buildings pale in comparison to that of lighting systems. However, every recently published version of energy codes has included an increase in requirements for power system components.
A key driver of the trend to increase code requirements can be attributed to the pursuit of special energy-sustainability certifications, such as U.S. Green Building Council's LEED requirements. LEED and other certifications continually raise the bar in differentiating buildings from what is defined as a minimum baseline. The international energy codes, in turn, have kept pace by raising their own standards on what is considered code-minimum. To wring out more energy from building systems, energy codes have been trending to include smaller contributors to building energy profiles. That is, moving on to the "little fish" to benefit from a cumulative effect.
Enhancing basic energy codes
The International Energy Conservation Code (IECC) and ASHRAE, Standard 90.1: Energy Standard for Buildings Except Low-Rise Residential Buildings form the basis of most adopted energy codes, yet these organizations have recently issued special sustainability or "green" versions to supplement their respective codes. The International Green Code Council (IgCC) has introduced a 2012 code to supplement the IECC for improved building sustainability. Likewise, ASHRAE created ASHRAE Standard 189.1: Standard for the Design of High-Performance Green Buildings for the same purpose, which serves as an alternate compliance path to IgCC, where adopted.
In relation to power system components, IECC has evolved from metering individual dwelling units (the only power systems requirement for the first few versions) to today's provisions. That is, IECC requires the previously metering mandate, but now also requires minimum transformer efficiencies and minimum motor efficiencies. IgCC supplements these with minimum requirements for the control of plug loads, water dispensers, refrigerated cases, additional transformer efficiencies, voltage drop, and also a section on renewable energy systems.
ASHRAE Standard 90.1: Energy Standard for Buildings Except Low-Rise Residential Buildings has evolved in a similar fashion. Early versions contained requirements for voltage drop and motors, but grew to include requirements for receptacle control, electrical energy monitoring and reporting, minimum transformer efficiencies, and minimum requirements for elevators and escalators. ASHRAE Standard 189.1: Standard for the Design of High-Performance Green Buildings includes additional requirements for renewable energy infrastructure and energy-consumption management.
The future of codes and standards
Authorities having jurisdiction (AHJs) have been increasingly proactive in adopting the latest versions of international energy codes or implementing them into their locally written and maintained codes; and not only the base codes. Some have also adopted portions of the sustainable code supplements and require a minimal level of LEED certification as well. In certain cases, AHJs go beyond the aspects of these codes and add their own energy-conservation requirements. For example, a requirement for the capability of demand-responsive lighting controls can be found in California's Title 24.
As the pace of AHJ code adoption increases, it can be anticipated that the content of requirements for components of power systems will evolve faster. After observing energy codes change for the past decade, engineers can speculate on where the next bars will be set for power system components. Below are thoughts on how codes can change going forward:
- Code minimum efficiencies for motors and transformers have increased with cadence. This coupled with sustainability certification requirements has pushed the advancement of technology for these components. So as technologies progress, these components may see the minimum-efficiency bar raised even more. It can also be anticipated that minimum efficiencies will be mandated for other equipment types, such as power-conversion equipment like uninterrupted power supplies and variable frequency drives.
- It is known that the efficiency of many power system components increases with loading. We may see mandated "right-sizing" requirements for equipment to reduce losses and conserve on materials.
- The percentages of controlled power outlets may increase, in addition to including more load/equipment categories beyond water dispensers and refrigerated cases.
- There are special code requirements that exist in energy codes for certain occupancies, like residential and retail. Other occupancies may enter the mix, especially large-load occupancies, such as data centers.
- The concept of demand-response controls is not new for the industry, as utility companies have used this in dense markets via voluntary programs or even involuntary emergency measures. However, this concept is relatively new to building codes. Some jurisdictions require these concepts via lighting and HVAC control systems, where they are not difficult to implement due to the programmable nature of the control equipment. But the table may be set for this requirement to drift into power systems. The advent of controlled power outlets and utilization equipment can progress to a requirement for these controls to be tied to a demand-response system.
- New sustainable code requirements show tendencies toward providing more provisions for renewable energy sources. The new technologies developing in solar energy collection are making it more viable to use in areas that traditionally had unattractive payback periods. History shows the energy and sustainable building codes will advance their requirements to coincide with these developments for widespread use.
Current code-adoption trends indicate more code requirements geared toward power systems in the near future. Through the past progression of code requirements related to lighting systems and controls, consulting engineers have grown accustomed to adapting designs to meet code-mandated demands. The industry needs to be prepared for another layer of implementation for power systems.
Michael A. Starego, PE, LEED AP, is associate principal engineer at Southland Industries.