With energy-consuming equipment, such as water heaters and refrigerators, we have good data on energy consumption and can set clear standards accordingly. In some product categories—clothes washers, for example—Energy Star standards were adopted because those standards provide a high enough threshold to represent just the very top segment of the product market (less than 10%). In other product categories—e.g., refrigerators and dishwashers—we set a higher threshold than ENERGY STAR: for example, exceeding those standards by 10% or 20%. With lighting and lighting control equipment, certain generic products qualify, such as compact fluorescent lamps and occupancy/daylighting controls, while in other categories only a subset of products qualify. In some cases, products that meet the energy efficiency requirements are excluded, because of evidence of poor performance or durability. Microturbines are included here because of the potential for cogeneration (combined heat and power) that they offer.
Once we’ve considered low-emitting products and those that prevent moisture problems, we also consider green ventilation products, filters, radon mitigation equipment, and other equipment and devices that help to remove pollutants or introduce fresh air. Because ventilation equipment is standard, we only recognize products that are particularly efficient or quiet or which have other benefits, such as heat recovery.
Panasonic's Whisper Comfort ERV achieves 1.74 cfm/W at 66% SRE. Designed for homes up to 1750 ft2, the Whisper Comfort includes a built-in Frost Prevention Mode and carries a three-year warranty on all parts.
Heat-recovery ventilators (HRVs) and energy-recovery ventilators (ERVs) are mechanical air-exchange systems that can capture up to 90% of the heat content from stale indoor air being exchanged for fresh outside air. These products work by passing the air streams through a heat-exchange core, generally made with multiple aluminum or plastic plates.
HRVs capture heat from the outgoing air during heating season to warm the incoming air. During the cooling season, "coolth" from often-air-conditioned indoor air is transferred to the warmer incoming fresh air to help prevent warming the building or minimize air conditioning loads. ERVs also provide humidity conditioning using a desiccant wheel or plates made of a permeable material; these help retain indoor moisture during the heating season and exclude it during the cooling season.
The efficiency of the heat exchange is dependent on both the equipment and the climate. Most systems are balanced: the same volume of air is exhausted and taken in.
While there are not (yet) Energy Star standards for HRVs and ERVs in the U.S., Energy Star standards are in place in Canada. Effective July 1, 2012, Tier 2 standards took effect for all of Canada (U.S. Climate Zone 6 and higher). Energy Star listed products must have a minimum "sensible heat-recovery efficiency" (SRE) at 32°F (0°C) of 65% and a minimum SRE at –13°F (–25°C) of 60%. The "fan efficacy" for models with SREs below 75% must be at least 1.2 cfm per watt (0.57 L/s/W) and for models with SREs of 75% or higher the fan efficacy must be at least 0.8 cfm per watt (0.38 L/s/W). GreenSpec lists products that have earned Energy Star certification against these requirements, with exceptions for high-performing products that haven't yet earned certification.
EAc1: Optimize Energy Performance
EAc1.3: Optimize Energy Performance—HVAC
EAp2: Minimum Energy Performance
EAp2: Minimum Energy Efficiency Performance
EQc2: Increased Ventilation
EQp1: Minimum IAQ Performance
IEQc2: Increased Ventilation
IEQc2: Increased Ventlilation
IEQp1: Minimum IAQ Performance
Ratings and Commentary