Truly Net Zero in Norway: The ZEB Pilot House

The house, which is 200 square meters in size (2,152 square feet), was purposefully sized to replicate an average single-family residence. While no one actively lives in the building, the building has become a demonstration platform to facilitate learning opportunities related to building methodologies for energy zero or energy positive houses with integrated sustainable solutions.

The house was built in Larvik, Norway, an area where summer temperatures vary between 20 to 26°C (68-78°F) and winters can routinely drop to -15°C (5°F). The climate has low relative humidity and the designers mentioned that the climate in northeastern cities such as Boston, Massachusetts is similar—so it could work in many areas of North America. 

Main Sustainability Features of the ZEB Pilot House 

Throughout the design and construction phases, the ZEB Pilot House aimed to include as many sustainable elements as possible; it was also mandatory to document and verify that 100 percent of carbon dioxide emissions were offset. The zero carbon emissions were not only calculated from the operation of the home (such as heating and cooling systems, lighting, appliances, etc.), but also from the embodied energy of the materials used in the home. According to the Snohetta website, “the focus on carbon emissions associated with building materials represents a new direction in the vital drive toward a sustainable construction industry.” 

While most sustainable home builders focus almost exclusively on the CO2 emissions associated with the operation of a home, a recent report titled “The Greenest Building: Quantifying the Environmental Value of Building Reuse” finds that in many cases replacing an older, less energy-efficient home with a new high-performance home will take an average of 80 years to offset the ecological impact (including the emissions) of the construction. 

Kristian says that the zero carbon emissions were analyzed “from materials and operations, plus energy, reclaimed materials for viable building components, great daylight access, and air quality.” He adds that “the house is also programmed to a life-long standard, meaning moving houses due to disability or frailty is unnecessary during a lifetime.” This feature of adaptable design is also significant, as it can reduce the need for new housing stock by allowing homeowners to spend a lifetime in a sustainable home rather than moving frequently, renovating, etc.

The ZEB Pilot House also includes renewable energy production with photovoltaic (PV) and solar-thermal panels integrated into the building envelope. The home uses solar panels for electricity to operate systems lighting, appliances and plug loads, etc., and solar thermal for heating and hot water. It also relies on a shallow geothermal ring at two to four meters depth. A heat exchanger extracts warmth to supplement the ventilation and heat circulation on the waterborne systems. 

The ZEB includes a rainwater collection system with a 5,000-liter tank submerged beneath the southern part of the house. The run-off from the roof is drained through simple infiltration and utilized for flushing toilets and irrigation. The greywater collection operates in the same way, using heat recapture for further efficiency.

However, the ZEB Pilot House team quickly points out that surplus renewable energy does not simply mean that homeowners should have the “right” to consume that energy through extra travel or more energy-consuming home devices. “While surplus free energy is a luxury, it is nonetheless important to keep in mind that there should be a balance,” Kristian believes. “We should be wary of contributing to a culture of excess. The house offsets the embodied emissions in all its materials, including PV—so simply adding more PV wouldn’t have been an option. It is a very tightly wound and highly specific solution with some nice upsides.”

Lessons Learned from the ZEB Pilot House

The ZEB Pilot House has helped to develop further understanding of building performance and the potential for zero-emission buildings using today’s building materials and off-the-shelf technology. Kristian further explains that “what has been the most interesting has been the study of how scaled down this technology can be—rather the antithesis of current trends of massive deployment of technological compensation and outdated system design.”