Net Zero Energy Building – A quick reference guide to energy-neutral, sustainable building

What is net zero energy building (NZEB)?

Net Zero Energy Building is method of design and construction that aims to achieve an energy efficient, grid-connected building, enabled to generate energy from renewable sources to compensate for its own energy demand.  As a result, these types of buildings boast a net zero energy consumption, such that the total energy used by the building on an annualized basis is roughly equal to the amount of renewable energy created on the site or at a nearby location.

Building owners and developers have demonstrated greater interest in developing zero energy buildings to meet corporate goals and regulatory mandates and the building and design community is rising to the challenge.  In fact, in many cases, they are helping to spearhead progressive projects that are truly marvels of ingenuity, engineering and forward-thinking design. 

Zero energy buildings are optimized to use passive solar heat gain and shading, combined with thermal mass, to stabilize temperature variations throughout the day.  They include a wide variety of energy efficiency measures—some highly complex and others quite simple—such as high efficiency heating and cooling equipment, appliances, windows and doors, as well as added insulation, natural ventilation, air sealing and more advanced renewable energy solutions such as solar photovoltaics and geothermal energy systems.

Net zero energy building is most commonly associated with commercial buildings, but it is possible for any structure to be net zero, including residential homes, as the concept is applicable and scalable to virtually any sized structure, whether a building is an expansive multi-use facility or a tiny home. The concept is even scalable to entire net zero campuses and communities.

How codes and standards guide net zero energy construction

Currently, building codes exist to help guide designers, architects, builders and contractors achieve more energy efficient and sustainable buildings than in years past.  In the United States, building industry professionals can look to the IECC, which has been adopted (in some version) in approximately 44 states and territories (although nearly a third are still using older versions of the code, dated 2003 - 2009).  ASHRAE 90.1 provides significant guidance across North America, while IgCC is another valuable resource.  In Canada, there is the NECC (National Energy Code of Canada), and the NECB (National Energy Code for Buildings).

Energy use, its associated carbon footprint, and its impact on people and the planet have cast a sharper focus on the need for stricter and more progressive energy and building codes.  However, there are a variety of challenges to their development.  As industry professionals and officials look to design newer codes to specifically address NZEB—especially as governments drive toward tighter energy targets by 2030—there is still no consensus on how to design code to move buildings towards NZEB, how that code should look, or even how to ensure the buildings actually achieve NZE post-construction or during operation, management and occupancy.

Ensuring buildings are not only designed to NZEB, but actually perform to NZEB standards would require post-construction reporting and analysis and a framework for oversight and enforcement.  It would require measurement of actual energy use.  However, today’s codes and standards are based on proxies for energy with no requirement to actually quantify the end result.  They are also gaps in types of energy uses that are included in energy calculations, leaving some uses unaddressed. To reach the goal of net-zero energy buildings, these methods must change. Modeling capabilities must improve, and actual outcomes must be measured.

Mindsets are a hurdle to NZEB that also cannot be overlooked.  A barrier to the implementation of NZEBs is changing our thinking with respect to cost, investment and return.  Building owners and homebuyers will need to better understand the upfront costs versus savings on a monthly, annualized and lifetime basis.  It can sometimes be difficult to get people to buy in to a long-term strategy.  Technology and solutions also need to be better promoted and understood by those who have the ability to influence decision makers within the industry and on the owner side, as well. 

Government at all levels throughout North America have recognized the urgency in taking climate action and improving sustainability measures.  In fact, thousands of cities in North America—and around the world—representing millions of citizens, have declared states of climate emergency.  The idea is that the first step to solving a problem is acknowledging that there is one.  Most recognize that significant action is required to stop the damaging effects of climate change and carbon pollution.  As a result, governments are launching various measures, programs and initiatives to combat climate change and contribute to their overall climate reduction strategies. 

The built environment is the primary focus.  Yet, the question remains: how can we boost the adoption of Net Zero Energy Buildings and bolster wider acceptance of zero energy building technology?

Currently, there is a mix of subsidies and financial incentives offered in cities and regions throughout North America aimed at increasing the amount of net zero energy buildings or near net zero energy buildings. 

The international community has clearly defined climate change as a priority and an opportunity to shift towards a low carbon economy, globally.

The Paris Agreement, adopted in December 2015 under the United Nations Framework Convention on Climate Change (UNFCC), is a commitment to accelerate and intensify the actions and investments needed for a sustainable low carbon future, to limit global average temperature rise to well below 2°C above pre-industrial levels, and to pursue efforts to limit the increase to 1.5°C.

As a first step towards implementing these commitments, Canada developed the Pan-Canadian Framework on Clean Growth and Climate Change. The Pan-Canadian Framework has four main pillars:

• pricing carbon pollution;
• complementary measures to further reduce emissions across the economy;
• measures to adapt to the impacts of climate change and build resilience; and
• actions to accelerate innovation, support clean technology, and create jobs.

In the United States, a number of cities and states have implemented measures, energy and carbon reduction targets, and in some cases legislated change to achieve the transition to a low carbon future.  Such examples can be seen in places like California, where $3.2 billion dollars in subsidies and incentives have been earmarked to help the net zero energy construction gain greater traction, and in New York, with its recent introduction of the Climate Mobilization Act that sets forth stricter energy requirements for new buildings and retrofit construction.

The World Business Council for Sustainable Development has launched a major initiative to support the development of ZEB and help to make ZEB a reality by mobilizing large global organizations.

It’s clear that there is a strong mandate for change.  It’s not so much a matter of if NZEB construction will become a greater part of the built environment but how and how quickly.  While codes haven’t quite caught up, many in the building community are already embracing solutions that can make a significant difference.

The role of the building envelope

To achieve net zero energy buildings, optimization of building energy efficiency typically considers the following: (1) lighting, (2) the walls and roof, (3) glazing, (4) heating, (5) ventilation, (6) air conditioning, (7) renewables (8) soft costs, and (9) the building usage and behaviours of the occupants.

Each of the above variables work together to ultimately reach the goal of net zero energy.  However, an air-tight, highly-insulated building envelope is an integral part of the NZEB strategy.  After all, the other efficiency measures may be negated if conditioned air flows out of the building unchecked.  To that point, insulation represents significant potential energy savings.  For example, ROCKWOOL stone wool insulation can help buildings realize heating energy savings of up to 70 per cent, reducing dependency on fossil fuels.  In 2018 alone, ROCKWOOL manufactured enough stone wool building insulation to save up to 200 million tonnes of carbon emissions throughout its lifetime use, which is equivalent to more than 43,000 wind turbines running for one year. 

ROCKWOOL stone wool insulation products for residential and commercial applications are available to help achieve even the most ambitious energy goals including NZEB.  ROCKWOOL stone wool insulation can be used in virtually all types of applications from continuous exterior insulation, rainscreen, and roofs to exterior and interior walls, basements, ceilings, attics, underslab, and more. 

To achieve high performance buildings, comprehensive services are available from ROCKWOOL’s building science team including full building energy modelling and thermal analysis to help architects, designers, specifiers, contactors, building owners and energy consultants maximize efficiencies.  A well planned and integrated team approach is typically necessary to achieve NZEB.  ROCKWOOL can help make the journey smoother.  Connect with ROCKWOOL Building Science Team.

Project Profile - A look at a progressive net zero energy building

A high-performance net zero energy home—the family home of Atmosphere Design Build principals Mela Breen and David Good (designer and builder)—the Good House project is informed by Passive House principles, embodying the tenents of resiliency, efficiency, health and comfort, while also reflecting a beautiful site-specific design that complements its natural surroundings.

To achieve its goal as a net zero energy building, reaching the highest levels of efficiency while also opting for sustainable materials, the Good House—the Fine Building Home of 2018--relied on ROCKWOOL stone wool insulation to super-insulate the structure, including walls, roof, and underslab.  Four inches of ROCKWOOL Comfortboard™ 110 rigid board insulation creates a continuous layer of insulation on the exterior of the home, helping to keep temperatures inside the home stable, protecting it from moisture and providing critical passive fire protection, an important consideration, given the Good House’s location inside one of California’s wildland urban interface zones.  Five inches of ROCKWOOL Toprock® provides maximum efficiency and fire safety for the roof system, while ROCKWOOL Comfortboard™ 110 also prevents heat loss below the home’s slab foundation.  In addition to its energy efficiency and its resistance to fire, ROCKWOOL was chosen for its ability to help create a vapor open assembly with high drying potential, to avoid moisture issues and prevent mold and mildew in California’s hot and humid climate.  The sound absorbency of ROCKWOOL products were also key to occupant comfort, given that the home is situated near a highway and soundblocking was a important consideration.  Finally, ROCKWOOL’s sustainability profile, natural raw materials and high recycled content were an ideal fit with Atmosphere Design Build’s own principles on sustainability and responsible building practices. 

The complexity of the design, with its cantilevers and steel deck foundation, required a heightened attention to the air sealing and insulation details. In addition to the highly-insulated envelope with ROCKWOOL insulation, all the connections between interior and exterior structural members are meticulously detailed to avoid thermal bridges, and triple pane European windows and doors are used to maximize light, comfort, and performance. A CO2 heat pump water heater provides the most efficient domestic hot water delivery. Balanced heat recovery ventilation offers high indoor air quality and uniform temperature distribution. Indoor climate control is provided by super efficient ductless mini splits. A 6.5 kw roof mounted photovoltaic system is installed to offset the home’s energy usage (including the charging of an electric car) – creating a zero net energy building.

Net Zero Energy Buildings – Striving today for a better tomorrow

With energy conservation and carbon reduction key priorities, it is in the collective interest of all to encourage and perhaps even legislate net zero energy building as a code requirement.  However, it remains a very complicated and controversial solution with its own inherent challenges.  Until the industry figures out the best approach, strategies like stretch codes and voluntary programs can help shift the industry toward net zero energy buildings and improve acceptance of some of the proposed changes.

The building envelope will remain a key building component to maximize efficiency, and insulation will remain one of the most cost-effective solutions.  Much of a building’s energy savings will be achieved through the building envelope – essentially resisting heat flow and improving overall performance. 

Net zero energy buildings can be part of path to more sustainable and liveable cities.  While regulation undoubtedly will play an increasing role, the choice we make for our buildings today will continue to have an impact on our planet—and our pocketbooks, for that matter—for decades to come.  Consider that, globally, 50 per cent of existing buildings will still be in use by 2050.  Of course, the larger concern is that we are running out of time to stave off the consequence of maintaining the status quo.   Most certainly, we must ask ourselves, what can we do today to make a difference for tomorrow?  Net zero energy building is one solution to reach energy and carbon reduction targets. Choosing sustainable, efficient stone wool insulation is another. 

Leadership in Net Zero Energy Building – Associations and more

Climate change is a scientific fact, and so we, too, must change our thinking and our practices in order to protect people and the planet.  A number of organizations are leading the charge in championing Net Zero Energy construction in an effort to bring it into standard practice.

World Green Building Council - The World Green Building Council, and the Green Building Councils participating in the Advancing Net Zero project (project steering committee), are dedicated to supporting market transformation towards 100% net zero carbon buildings by 2050. See the infographic that highlights their framework including key target dates, definition for net zero carbon buildings, the action pathways being taken by our GBCs, and the key principles that are guiding their actions. These principles ensure alignment and commonality across global markets, whilst enabling specific market applications.

International Living Futures Institute - The International Living Future Institute (ILFI) is a nonprofit working to build an ecologically-minded, restorative world for all people. Using principles of social and environmental justice, ILFI seeks to counter climate change by pushing for an urban environment free of fossil fuels. ILFI runs the Living Building Challenge, which is the world’s most rigorous green building standard.  It includes three types of certifications: Living Building Certification, Petal Certification or Net Zero Energy Building Certification.  The ILFI also runs several other programs: the Living Product Challenge, the Living Community Challenge, and the Reveal, Declare and Just labels. These programs develop a green framework for living in a 21st-century world. 

The Net-Zero Energy Coalition - The Net-Zero Energy Coalition is a change agent, enabling the industry to more rapidly transition to building zero energy, thereby reducing carbon emissions across North America. Members, partners, and sponsors will benefit from extensive industry exposure, connections to net-zero energy leaders globally, and access to resources and funding for collective efforts. Building occupants will benefit from more comfortable, healthier, lower cost, responsible living environments that last for generations to come.

In early 2014, NZEC produced a report for NRCan, entitled “Coordinating and Unifying NZE Efforts in North America,” and documented 146 organizations and 100 builders focused on zero energy.  This demonstrates industry momentum, and an opportunity to consolidate and coordinate efforts toward greater market adoption.  The Net-Zero Energy Coalition’s role is a backbone organization to facilitate this collaboration and transfer knowledge within the industry.

Founded in Canada in January 2006, the Net-Zero Energy Coalition has grown to serve all of North America.  Its mission is to accelerate market adoption of net-zero energy buildings and communities in order to make the built environment a positive asset on the balance sheet for the planet.

The Zero Energy Project - The Zero Energy Project is a non-profit educational organization whose goal is to help home buyers, builders, designers, and real estate professionals take meaningful steps towards radically reducing carbon emissions and energy bills by building zero net energy homes and near zero energy homes. We envision the day when positive energy homes, which produce more energy than they consume, will power electric vehicles as well as homes, so that everyone can live well with less expense and without fear of energy price spikes, while greatly reducing our carbon emissions.