Net Zero Energy Buildings Raise the Bar for Performance and Comfort
This rigorous designation is a proof of concept developers hope will drive market demand
An eight-minute drive from Boulder’s Pearl Street Mall, a historic feat of architecture, building science, craftsmanship and engineering nears completion. Boulder Commons, which will generate as much energy as it requires, will be the largest U.S. multi-tenant commercial development to experiment with net zero leases.
Along Colorado’s Front Range, several recently completed developments have been recognized by the Department of Energy as Net Zero Energy (NZE) or Net Zero Ready. This rigorous designation is a proof of concept developers hope will drive market demand for more and possibly catalyze the adoption of higher building standards. NZE properties are capable of returning as much energy to the grid as they “borrow” through geothermal heating and cooling, photovoltaics (PV) and energy-efficient building methods.
According to Rocky Mountain Institute (RMI), a nonprofit energy think tank, building operations account for 39 percent of U.S. carbon emissions. That makes them the largest end-use energy sector, surpassing agriculture or transportation.
In the case of Boulder Commons, innovative net-zero leases are designed to align the interests of landlord and tenant, resulting in a win-win arrangement that helps to optimize building efficiency. Typically, there’s a divergence of interests between landlords, who pay for efficiency upgrades, and tenants, who benefit from lower utility bills. Developer Morgan Creek Ventures and RMI, the premier tenant at the Commons, worked together with law firm Holland & Hart to design the lease. It includes a plug load energy budget for each tenant that, if exceeded, requires them to purchase Renewable Energy Credits. It also unbundles parking from office space, incentivizing alternative transportation.
Just over an hour north of Boulder Commons, Revive Fort Collins, built by Philgreen Construction, nears completion. The same goes for the RidgeGate development in Lone Tree built by Thrive Home Builders. These two properties were the only two multi-family residential developments in the U.S. to receive the Department of Energy’s 2016 Housing Innovation Award.
This is a big deal. “Housing Innovation Award winners represent the top 1 percent of builders across the country who successfully demonstrate they can meet the federal government’s most rigorous specifications for high-performance homes,” says Sam Rashkin, chief architect at DOE’s Building Technologies Office.
At Revive, architectural features such as the thoughtful placement of windows ensure both in-home privacy and views of nature. Homeowner Linda Vescio, an avid gardener, says she’s sold more energy back to the utility than she’s bought. That’s due to her 8-kW rooftop PV system and the efficiency of geothermal heating and cooling.
“We always have negative energy bills,” she says. “What we’ve been doing is covering our water bill with our electric bill.”
Geothermal technology, including ground-source heat pumps, efficiently heats and cools air by tapping into the constant, 57-degree (give or take) temperature of the earth beneath us. Little energy is required to adjust from there to a comfortable temperature.
“A good furnace is 90 percent efficient,” says Revive’s Development Consultant and Broker Sue McFaddin. “Geothermal is 300 percent efficient. For every electron you put in the ground, you get three units of energy.”
Many of the gains and losses in building operations are difficult to control because homes and offices are simply leaky — and utilities bills aside, that impacts health. Building methods that ensure airtightness and good ventilation, combined with the use of low-VOC (volatile organic compounds) finishes, provide a level of indoor air quality known to improve respiratory health, concentration and productivity.
Additionally, these properties don’t have gas furnaces or air compressors, eliminating most mechanical noise. Instead, methods including superinsulation, the use of energy recovery ventilators (ERVs), geothermal heating and cooling and high-performance windows maintain interior comfort. Other common features include 100 percent LED lighting, ENERGY STAR appliances, daylighting, WaterSense hot water distribution, low-VOC finishes and electric car-charging stations.