Ductless mini-split system heat pumps are similar to standard air-source heat pumps and can save up to 30 percent on heating and cooling costs over central air-conditioning systems (photo courtesy Daikin).
There’s green and there’s uber-green. Then there are builders who have a passing interest in green building technologies, but aren’t so sure about the costs or the benefits, besides energy savings. The benefits to the homeowners range from having green or eco-friendly homes to maintaining healthy lifestyles to paying lower utility bills. ERVs, geothermal heat, mini-split HVAC units, and heat pumps keep cool air flowing and the water hot.
As utility costs increase and more homebuyers say they’re interested in greener homes being able to list green technologies on the fact sheet, and how they save energy, can increase a buyer’s interest in your home over others like it.
The NAHB’s 2013 What Home Buyers Want survey reported that 67 percent of buyers want an environmentally friendly home or are concerned about the environment in general. They also want to know about a home’s projected utility cost, suggesting that eco-friendly features that lower utility bills would interest them. They would also be willing to pay an additional average of $7,095 to the up-front price of a home if that saved them $1,000 annually in utility costs.
Heating and Cooling by Mini-splits
In homebuilder Randall Lanou’s newly built green home, he installed Daikin ductless mini-splits to condition the house. “In a house this well insulated and this tight, you can bring hot and cool air to a core, and throw it out into the space, it doesn’t have to have a spider reach [as with ducting],” he says. “That makes the mini-split system super-efficient.”
Ductless mini-split system heat pumps are similar to standard air-source heat pumps. They have two main components – an outdoor compressor/condenser and an indoor air-handling unit. A conduit, which houses the power cable, refrigerant tubing, suction tubing, and a condensate drain, links the outdoor and indoor units. The main advantages of mini-splits are their small size and flexibility for zoning or heating and cooling individual rooms. Multi-zone models such as the one Lanou installed can have as many as four air-handling units connected to one outdoor unit. Each of the zones has its own thermostat.
Having no ducts, they avoid the energy losses (up to 30 percent according to the U.S. Department of Energy) associated with the ductwork of central forced air systems.
The system’s heat exchanger mixes cooler air from the heat pump with warmer interior air to create a healthier, and more efficient, house, according to Lanou.
Daikin mini-split heat pumps condition each room separately while avoiding the energy losses of central AC systems (photo courtesy Daikin).
Heat Pump Water Heater
Lanou’s home, which has been certified Emerald under the National Green Building Standard by the NAHB, also has an AO Smith hybrid heat pump water heater with a 50-gallon tank. The heat pump works by extracting warmth from the surrounding air, concentrating the heat and transferring it to the water. The cool dry air from the system is ducted into a root cellar where Lanou plans to store root vegetables and wine and brew beer.
AO Smith heat pump water heater (photo courtesy AO Smith).
ERV with Conditioning
Kevin Murphy, the owner of Newphire Building Corp., a small custom homebuilder in Chapel Hill, N.C., focuses on using green building techniques that save his clients thousands of dollars in energy and water bills each year. In his latest home, the Happy Meadows Courtyard House in Chapel Hill, Murphy has installed an energy recovery system (ERV) with an additional feature, the CERV or conditioning ERV. CERV by Build Equinox, is a ventilation system with integrated heat-pump conditioning capabilities.
The system pre-cools the air in the home while humidifying and pre-heating it in the cooler seasons, as necessary. The benefit of using energy recovery is the ability to meet the ASHRAE ventilation and energy standards, while improving indoor air quality and reducing total HVAC equipment capacity. Build Equinox’s CERV is a smart system with integrated sensors providing on-demand ventilation based on weather conditions, occupancy and more. Fresh air conditioning and energy recovery are both accomplished through the integrated heat pump. This module heats, cools, dehumidifies and exchanges energy. The system allows the homeowner to set levels of humidity and carbon dioxide and to monitor VOCs. The “CERVICE” option provides the homeowner with real time diagnostics from anywhere with Internet access. The system installs with traditional ductwork connections.
The CERV by Build Equinox HVAC system manages home ventilation and improves indoor air quality (photo courtesy Newphire Building Corp..)
Solar PVT (What the Heck does That Mean?)
Appliance giant Whirlpool teamed up with Purdue University to renovate an 86-year-old home with the plans to make it Net-Zero in self-sufficiency for energy, water and waste. With all the technology in this home, simplicity may be key. Homebuilder and general contractor Grant Giese, owner of Green Goose Homes in Lafayette, Ind., was most interested in installing SolarZentrum PVT panels. The combination system called PVT (photovoltaic thermal) not only provides electricity but also will heat domestic water for the home. A series of tubes are located behind the solar cells and circulate water behind the panels. The water is warmed by the heat generated by the sun’s rays on the panels. The thermal exchanger has two benefits: the heat can be used to heat water for domestic use, and the system cools the panels that become less efficient as they get hotter. SolarZentrum says the panels are 30 percent more efficient at generating electricity than standard PV panels.
SolarZentrum PVT photovoltaic and thermal panels generate electricity and warm water (photo courtesy ZolarZentrum).
The Happy Meadows Courtyard, which will most likely be certified “Emerald” by the NAHB, is heated and cooled by a ClimateMaster ground source heat pump with a Nest thermostat, which learns the homeowners’ tendencies and adjusts the heating and cooling to fit their rhythms and save energy.
Whirlpool’s ReNEWW house is heated by a GeoComfort geothermal system by Enertech Global. Contractors dug three 250-foot vertical wells that will heat the home’s three levels. The basement and first floor will be a forced-air system while the second floor bedrooms will have a hydronic system as well as minisplits in each bedroom that will allow each room to be heated or cooled separately. The ReNEWW house is meant to be a live-in laboratory to investigate various green home technologies and find how they work in an actual home.
While these builders make green a priority, they also show that by selecting technology, any homebuilder can add “green” to their fact sheets.