Energy efficiency is of paramount importance to all facilities that employ electrical systems and different measures are used to help assess the efficiency of these systems by sector. In the residential sector, one such measure is the Home Energy Rating System (HERS), a standard which is governed by the Residential Energy Services Network (RESNET) and which can play a role in a home’s value as well as dictate its eligibility for certain mortgage rates and utility rebates; the International Residential Code (IRC) is yet another.
Following, experts from leading manufacturers Panasonic and Broan weigh in on the mission of HERS, RESNET and the IRC, how they apply to the residential ventilation industry and how specific products can help builders, contractors and other channel members comply with and/or enhance their rating.
The HERS Index and RESNET Explained
According to Patrick Nielsen, global technical products manager at Broan, the HERS Index is a nationallyrecognized system for inspecting and calculating a home’s energy performance. “HERS is calculated based on software modeling which incorporates a number of energy-related inputs, including how airtight the home is (based on a blower door test), how it’s insulated, etc.,” he said. “Like a golf score, the lower the better, as 100 corresponds to a 2006 code minimum reference home and zero corresponds to a Zero Net Energy home.”
Jeff Bierl, field technical support engineer and HERS rater at Panasonic, agreed. “The U.S. Department of Energy (DOE) has determined that a home with a HERS Index Score of 70 is 30% more energy efficient than a standard new home and a home with a HERS Index Score of 130 is 30% less energy efficient than a standard new home,” Bierl said. “According to the DOE, an energy-efficient home can help save anywhere from 5% to 30% on energy bills, and these savings both benefit homeowners and decrease load demand challenges faced by many utilities.”
Specifically, Bierl added, a home’s greater efficiency helps avoid the need for utility companies to construct new power plants or expand existing ones and also reduces maintenance needs on grids. “Builders and suppliers also benefit from knowing that components used in the building process have been installed to specifications and will minimize the risk of costly repairs and damage to a provider’s reputation,” said Bierl. “At the same time, consumers will benefit from the process by having a well-built, healthy home that’s more affordable to live in.”
Nielsen said that favorable HERS scores also aid in the sale of homes. “Home builders strive for low HERS scores so that they can market the energy efficiency of their homes to prospective homeowners and potentially enjoy utility company rebates,” he explained. “They also have the option in later versions of the energy code to meet performance path requirements based on achieving a maximum HERS score for their climate zone. Overall, suppliers/manufacturers want to be able to offer products that will help builders lower their HERS score.”
RESNET is the official organization that created the HERS rating system and certifies the HERS raters who are specially trained to rate homes. Specifically, “RESNET was founded in 1995 by the National Association of State Energy Officials and Energy Rated Homes of America and is a nonprofit membership corporation governed by a board of directors,” Bierl shared. “RESNET is a recognized national standards-making body for building energy efficiency rating and certification systems in the United States and its mission is to develop a national market for home energy rating systems and energy-efficient mortgages.”
Among other activities within its purview, Bierl said that RESNET created and maintains both the HERS Index to allow for easy comparison of energy performance of homes as well as the HERS H20 rating to compare indoor and outdoor water usage of homes. “RESNET is also involved in national training, certification and quality assurance standards for Home Energy Raters, governs two American National Standards Institute (ANSI) standards supporting energy and water efficiency in homes, and maintains four Standard Development Committees,” he said.
Contributing to Compliance
Our experts confirmed that certain products will help builders enhance a home’s HERS Index and/or comply with the IRC.
According to Russell Pope, industry development manager at Panasonic, “one of the most important considerations we’re recognizing is that most installations require a more powerful fan than what’s been traditionally selected. It used to be assumed that if a product was HVI-Certified at 0.1” static pressure (SP) and ENERGY STAR-rated with 0.25” that it would always meet the requirements after it was installed,” Pope said. “We’re learning that, more often than not, the actual installation requires a product that will overcome 0.375” SP versus the ENERGY STAR demarcation of 0.25.” What this boils down to is that you should select a fan that’s 50% more powerful than what one may assume,” Pope said of a product category reality that not only represents a consistent challenge but one which is well known by HERS raters.
Pope explained that one of the reasons why the installed pressure is so high is because the duct end termination can add a substantial burden to the load. He cited a recent research study conducted at Texas A&M University which documented that terminations can add up to .375” SP while exhausting 100 cubic feet per minute (CFM), which is only the termination without any consideration for duct work. “No wonder the field experiences challenges with installed performance—the bar has been set too low and we must raise it,” Pope contended. “This is exactly why Panasonic is pioneering change by voluntarily certifying products based on a real-world, true flow rating at 0.375” SP.”
“Overall, builders should look for ventilation products that are energy efficient in terms of CFM of airflow per watt, airtight in order to enhance the measure of their blower door airtightness and powerful enough to ensure that they’ll be able to move the required amount of air even after installed with some added SP (duct resistance),” Broan’s Nielsen noted. “Ideally, products also need to be quiet, as homeowners aren’t likely to use ventilation fans if they’re too loud; these situations increase the possibility of callbacks or, even worse, liability concerns due to excess moisture.”
According to our experts from Broan and Panasonic, the following products within their respective company portfolios will become increasingly instrumental to enhancing a home’s HERS index, complying with the IRC, and minimizing risk to builders and homeowners:
- Broan’s premium ZB-series UltraGreen™ fans are HVI-certified and feature multi-speed capability so that they can be set to run at a continuous lower level to meet the wholehouse ventilation requirement of today’s stringent codes but also ramp up to full power for showers. All models feature DC motors and are also available with attractive LED lighting and sense-on-rise humidity sensing to change levels automatically.
- Panasonic’s WhisperGreen Select™ is a top choice of residential energy raters when performance assurance is critical and a variety of upgrade options is desired. Available products in this family cover exhaust rates from 30 CFM to 150 CFM, incorporate LED-lighted standard nightlights and feature plug and play modules for condensation sensing, ASHRAE 62.2 programming, or motion sensors, enabling users to meet any code compliance challenge presented. These models are also HVI-certified to perform at 0.375” SP—an industry first!
- Broan’s Flex DC™ HVI-certified bath ventilation fans are great for new construction or room-side retrofits. In addition to extremely airtight housings and dampers, this series offers selectable CFM (50, 80 or 110) to ensure that your project isn’t red-tagged. All models feature energy-efficient DC motors and most feature LED-lighted options. Humidity-sensing models are also available.
- Panasonic’s WhisperFresh Select™ supply air fan incorporates the Built-in Pick-A-Flow™ airflow selector switch, which allows users to select their required airflow (50-150 CFM). WhisperFresh Select can be used to comply with the latest codes and standards, including ASHRAE 62.2, LEED and California Title 24, and its powerful electronically commutated motor (ECM) pulls the fresh air through the MERV 8 or optional MERV 13 filter (MERV 13 is recommended in urban areas with heavy traffic and industrial pollution or rural areas with wildfires or heavy pollen count). For tightly constructed homes that need a source of fresh air supply, the WhisperFresh Select is an excellent solution.
- Broan’s LoProfile DC™ HVI-certified bath ventilation fans are also CFM selectable (50, 80 or 100) and are ideal for tight spaces and multi-family applications, as they feature shallow housings that fit into 2x4 spaces. All models feature energy-efficient DC motors.
- When considering ventilation products for indoor air quality, Panasonic’s Intelli-Balance™ 100 Energy Recovery Ventilator is an excellent choice. The unit is a customizable, high performance, high efficiency energy recovery ventilator (ERV) that’s designed to help meet ASHRAE 62.2 requirements. This unique and cost-effective ERV was engineered for total versatility and installation flexibility in any climate zone and features a percent run timer as well as built-in controls that enable users to customize the supply and exhaust airstreams individually. ERVs are increasingly replacing heat recovery ventilation systems (HRVs) in cold climate zones and are the only option in hot, humid areas where an HRV simply won’t work.
An Update on the 2018 IRC
Created by the International Code Council and updated every three years, the International Residential Code (IRC) brings together all building, plumbing, mechanical, fuel gas, energy and electrical provisions and establishes minimum regulations for residential construction of one- and twofamily dwellings of three stories or less. Following, Broan’s Patrick Nielsen provides a helpful update on the newest 2018 version.
IMARK Electrical Now: How widespread will adoption of the 2018 IRC be this year?
Nielsen: Ohio, potentially Nebraska and many municipalities are adopting the new 2018 version this year. We’ve found that with past code revisions, a handful of states and key municipalities update each year.
IMARK Electrical Now: How does the 2018 IRC differ from the 2015 version as it relates to residential exhaust/ ventilation products?
Nielsen: The key change with the 2018 version involves the requirement that all exhaust equipment serving singledwelling units such as bath ventilation fans and range hoods needs to be listed and labeled as providing the minimum required airflow in accordance with ANSI testing standards. This essentially means that they need to be certified by a certification body—usually the Home Ventilating Institute (HVI) in the case of residential ventilation. Electrical distributors should make sure that the exhaust ventilation products they carry are certified (a certified products directory can be found at hvi.org). All of the same requirements for spot and whole-house ventilation are the same as in the 2012 and 2015 versions.
IMARK Electrical Now: What do any states that have adopted the 2012 or 2015 versions of the IRC and IECC (International Energy Conservation Code) require?
Nielsen: These states require two things. The first is minimum spot/local airflow rates. For instance, bathrooms require 50 cubic feet per minute (CFM) of actual delivered airflow. With typical ducting installations being less airflow-friendly than where bath fans are rated, a fan rated at 80 CFM is generally needed to ensure that the inspector will actually measure at least 50 CFM. The second requirement is whole house ventilation (unless this part of the code was amended). Today’s tightly-built homes are great for lower utility bills but can also cause problems with indoor air quality. The 2012 or 2015 versions of the IRC and IECC require a minimum amount of continuous ventilation airflow based on the size of a home, and this can be either exhaust (pulling stale air out), supply (pushing fresh air in) or a balanced approach (e.g., a combination of both). Heat Recovery Ventilators and Energy Recovery Ventilators are ideal solutions where balanced ventilation is desired.