Is Zero Net Energy a Feasible Goal in Housing?

Since the U.N. Intergovernmental Panel on Climate Change issued a 12-year deadline for massive, coordinated action to combat man-made climate change, the feasibility of the Green New Deal has taken center stage. But the type of change that’s needed to avoid an insurmountable slippery slope requires cooperation from more than government officials. Builders and property owners must also take action, and there’s never been a better time to seriously consider moves toward zero net energy (ZNE) use.

What is Zero Net Energy?

Sounds impossible, right? How can a modern building possibly generate more energy than it uses? Believe it or not, ZNE homes have already arrived. Buildings that produce as much energy as their residents consume are constructed not only with solar panels to produce energy, but also energy-efficiency optimization with features like airtight roofs, walls, windows and foundations.

The U.S. Department of Energy defines a ZNE building as one that produces as much energy through renewable sources as its uses over a designated period of time. With advances in both renewable energy production and energy efficiencies, zero-net energy is more attainable than ever.

Believe it or not, there are already at least 5,000 ZNE single-family homes in the United States, and as many as 100,000 per year are being built in California alone. According to the New Buildings Institute, the number of zero-net energy buildings in the United States and Canada has increased by 700 percent since 2010 and now includes 45 million square feet of commercial building space.

Attaining zero-net energy is also financially feasible. Sure, there are some up-front construction costs, but after zero net energy is achieved, the cost savings over the lifetime of a building can be massive. After all, the ongoing costs for energy after ZNE is reached are practically nothing. When constructing new buildings, the costs to achieve ZNE a small premium that is easily eliminated through saving on the costs of utilities.  

Zero Net Energy Homes

Late last year, California instituted the requirement that all new homes and multi-family residential buildings up to three stories high must include rooftop solar panels starting in 2020. Renewable energy mandates aren’t the only answer to climate change issues that plague the state.

One California developer has taken the initiative to provide ZNE homes since 2013. De Young Properties built its first ZNE home in 2013 and has since begun construction on three communities with more than 140 ZNE single-family homes in each. The homes sell at a premium of just $10,000 compared to non-ZNE properties, a cost Brandon De Young doesn’t see as an obstacle.

“Energy bills tend to be pretty high and onerous, and you usually have to sacrifice comfort for your energy bill or your energy bill for comfort, and we saw an opportunity to advance in this realm and become a leader,” De Young told CNBC.

Zero Net Energy Multi-Family Housing

Builders of single-family homes cannot wage the battle for ZNE alone, however. According to the U.S. Census Bureau, 53 percent of renters in the United States – almost 26.5 million households – reside in multi-family homes and properties. Considering an additional 280,000 multifamily units are expected to complete construction in 2019, there is ample opportunity to make a difference in America’s carbon footprint.

Property owners have more motivation to reach ZNE than merely fighting climate change. Research shows that energy-efficient properties have not only better occupancy rates but also higher asset value than other buildings. Likewise, as more consumers begin examining their own carbon footprints, ZNE will be less about getting a leg up on the competition and more about simply keeping up with competitors.

California again led the pack in constructing ZNE homes with the 2017 opening of Silver Star Apartments, the first ZNE multi-family housing development in Los Angeles. The 49 buildings boasted not only rooftop solar panels but also vertical solar facades to generate energy for residents. The project was honored as the Sustainable Innovation Awards Project of the Year in 2017. But that was only the beginning of a regional trend.

In addition to the innovative solar energy system, Silver Star Apartments also featured the following to reach its ZNE goals:

  • Occupancy sensors
  • Energy Star appliances
  • LED lighting
  • Increased insulation
  • Dual-flush toilets and low-flow showerheads
  • High-performance windows
  • Reclaimed wood flooring
  • Recycled glass countertops
  • iPad energy tracking displays

The iPad displays were included in the apartment design to not only provide energy efficiency to residents, but to engage them with their energy consumption. The displays allow tenants to see how much energy they are using, as well as understand how much energy their solar panels – wired on the roof and directly wired to individual meters – are producing.

While Silver Star was a new development, property owners can add many of the same features to existing construction. For example, a 25-percent reduction in energy use was achieved by one Washington development by installing a ground source heat pump for heating and hot water.

The same complex saw a 15-percent energy use reduction by upgrading the insulation in walls and ceilings and a 7-percent reduction by converting from ducted heating to hydronic floor heating. An additional 5-percent reduction in energy use was achieved by replacing windows with double-paned models with a U-value of .33 and with tightly sealed exterior walls and ductwork. Replacing lighting with high-efficiency LEDs and CFLs reduced energy consumption by another 5 percent.

In all, the development saw its energy use dropped to one-third of its prior use, and the existing usage was then supplied by the rooftop solar panels.

ZNE is “really quite possible in most multi-family [buildings], which are flat-roofed and don’t have the kind of equipment you typically find in the commercial office like big air handlers, chillers and so forth on the roof,” consultant Jerry Yudelson, who has authored more than a dozen books on green building, told Property Management Insider. “You’ve got room to run, and in the hotter parts of the country, like Arizona and Texas, you’ve got carports and other things that can also support solar panels.”

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