The Green Tech Production Home

The Green Tech Production Home

Nexus EnergyHomes blend sound green building techniques with innovative energy efficiency systems.

Step into a house built by Nexus EnergyHomes, and it may seem like any other.

But behind the freshly painted walls is a home that’s green to its core, using super-insulated shells made from SIPs (structurally insulated panels), green cement-fiber siding, bamboo floors, energy-efficient low-E windows, recycled carpeting and glass countertops — along with paints and building materials that emit low levels of VOCs (volatile organic compounds), which can aggravate respiratory conditions.

Nexus EnergyHomes are built super-tight for better energy efficiency and achieve an average HERS (Home Energy Rating System) score of 24 (the average new home is 100 and 0 means a home produces all its own energy).

But that isn’t all that makes these homes green. To help get such low HERS ratings, the homes are also chock-full of green and energy efficiency technologies.

The houses boast solar electric power, geothermal heating and cooling with ground-source heat pumps, water-saving systems, advanced energy recovering ventilation systems, Energy Star appliances, energy-efficient CFL and LED lighting and even home control and automation systems with energy monitoring and energy management.

Photo courtesy of Nexus EnergyHomes.Oh, and did we mention Nexus homes buyers receive an iPad or tablet computer to help control and manage their smart new green homes?

“People are looking for technology,” says Mike Murphy, executive vice president at Nexus EnergyHomes in Stevensville, Md. “iPhones and iPads are proof that people embrace this kind of technology. And now they can communicate with their homes in a way they never have before.”


Big Green Value

Nexus EnergyHomes has built about 40 homes, all meeting National Association of Home Builders (NAHB) Emerald certification standards for energy-efficient construction and the ICC 700 National Green Building Standard (NGBS).

These homes are also certified by Energy Star for Homes and the EPA’s indoor Air Plus program. Thus far, Nexus has built two homes that meet the Department of Energy’s Challenge Home program, and has won a Housing Innovation Award for production homes at the 2013 Solar Decathlon.

“The buyer concept has changed,” says Murphy. “[Homebuyers] are getting messages from big builders about high-performance homes, and they’re a little bit more educated in what a high-performance home contains.”

And yes, using all those green building materials and green technologies means Nexus EnergyHomes are more expensive than a typical production home.

Prices range from about $295,000 to $700,000. “Our homes cost 10 to 15 percent more. We don’t have any problem with that because we have a value product,” says Murphy.

So what’s in a Nexus EnergyHome that makes it so special?


Solar and Geothermal

Photo courtesy of Nexus EnergyHomes.Start with renewable energy sources. Nexus EnergyHomes uses what it calls GeoSolar, with geothermal or “ground-source” heat pumps that pull heat from below ground and solar photovoltaic panels that produce electricity.

The geothermal systems also act as cooling sources in the warmer months by pulling warm air from the home, much like a refrigerator does. Because of this, Nexus homes don’t require loud and energy-intensive air conditioning systems.

Nexus uses GreenBrilliance and REC Solar panels and stresses that it only uses non-Chinese panels, which have taken hits of late due to poor production practices in some Chinese facilities.

With the deferred tax credit of 30 percent for renewables, buyers can get back $16,000 to $23,000 on the cost of these systems.

Photo courtesy of Nexus EnergyHomes.

Nexus is also starting to use Dow Powerhouse Solar Shingles that are actually roofing shingles with thin-film solar collectors — offering the systems as options.

The company is considering using the Dow shingles as the baseline solar array for a high-end community in Frederick, Md., with home prices in the $800,000 and up range.


Water Savings

Inside its homes Nexus uses low-flow WaterSense fixtures for water savings, and in its new high-end Frederick community, Nexus is adding rainwater collection with underground cisterns that feed irrigation systems so lawns and gardens can be fed using as little water as possible. The irrigation systems will be controlled by sensors that detect ground moisture and rain so they won’t water unnecessarily.

The energy required to heat water is also saved via a desuperheater that uses the heat built up from ground-source heat pumps to help heat water. In the summer, heat is removed from the home and into the hot water tank to warm the water. Murphy says Nexus is saving an average of 50 percent on hot water heating with the system.

Nexus is also negotiating to use a manifold plumbing system that employs a manifold, usually near the service entry, and flexible cross-linked polyethylene (PEX) tubing to deliver water more efficiently. The PEX tubing eliminates many of the elbows and connections that copper tubing requires, resulting in better water pressure.

Air Filtration

An oft-overlooked aspect of green homes is ventilation, which becomes vital as houses are built tighter to increase efficiency. An unfortunate bi-product of energy efficiency can be stale, unhealthy air—if the house is not ventilated properly.

“One area gaining traction is the clean-air environment,” says Murphy, as a growing number of people suffer from respiratory illnesses or allergies.

Nexus’ solution is multifaceted, with an energy recovery ventilator (ERV) that circulates the air 24/7 and transfers heat and humidity as needed between incoming and outgoing air, as opposed to a heat recovery ventilator (HRV) that just transfers heat alone.

The ERV constantly equalizes the pressure in the house, and its HEPA filter eliminates particles as small as .03 microns. Once in the home, the fresh air is filtered through a MIRV filter and then through an “elimination chamber” in which a photocatalytic purifier using a titanium dioxide screen and ultraviolet light breaks down particles as fine as .001 microns as well as VOC pollutants including formaldehyde, exhaust fumes, benzene, toluene, and odors like ammonia and hydrogen sulfide.

Nexus adopted the two-step in-line purification system from a company that provides those systems for luxury yachts to eliminate mold and mildew.

“[With homes so tight], you have to scrub the air and make sure you’re getting the mold and mildew and to keep [healthy] humidity levels,” Murphy explains.


Home Control and Energy Management

Homebuyers can also see their energy usage and energy production, as well as control parts of their homes with a NexusVision system that comes standard in each Nexus house. The web-based myNexus Home portal contains apps for Eragy energy monitoring, Enphase solar monitoring, and home control systems.

The Eragy system measures electricity usage in the whole house and at the circuit level via current transformers (CTs) that clip around the electrical mains and circuit wires in an electrical panel. Enphase’s Enlighten app monitors the solar production. And’s emPower system provides control of security, two to four lights, digital door locks with remote locking, and climate control with one thermostat.

Homeowners can operate it all via a smartphone or the iPad/tablet that comes with their house.

The web-based myNexus Home portal also contains the plans for the home, all warranty data associated with products in the house and warns you when a warranty is about to expire, as well as any plaques, documents and certifications for the home. It’s basically a user guide-plus, explains Murphy.

“Technology is a big part of what we do,” Murphy says. “It’s great to create a high-performance home, but you also need a way to show that to the homeowners.”

Murphy relates the story of one homeowner who says he never realized how much energy he was using until he turned on the vacuum cleaner and saw his energy use spike. Now he vacuums as fast as he can. And in Nexus’ North Pointe development in Frederick, homeowners have get-togethers to compare their diminished energy bills.

Making the NexusVision system more proprietary has been on the to-do list for Nexus EnergyHomes, and it may act on that promise now that energy monitoring company Eragy has been purchased by home control company Control4, which has informed Eragy dealers that it will service Eragy only through the end of the year.

Nexus even keeps a full-time R&D person to keep up on the latest technologies to include in its homes, so the company can keep producing the highest performing homes. Murphy calls it “an evolution of products that will create the next generation of homes.”


Lasting Value for Homebuyers

All that technology is great, but what’s the value proposition to homebuyers?

“[Homes like this] save people x amount of money over x amount of years,” says Murphy. “At resale they’ll still be holding that value of saving money. And [homebuyers] are going to be able to sell their home quicker and transition into their next homes.”

There’s also a lifestyle value that can be stressed to a green homebuyer. “There’s a value in just having a well-built home that’s very tight and quiet inside,” says Murphy. “There’ a serenity in having a quiet home.”

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