“Energy-Positive” Buildings
Buildings account for 30% of global energy consumption
The operation of buildings accounted for 30% of global energy consumption in 2021, according to the International Energy Agency (IEA).
And, including energy consumption associated with the production of cement, steel, and aluminium used for building construction, the share increases to 34%.
In terms of greenhouse gas emissions, buildings represent around 39% of global greenhouse gas emissions, including around 28% in operational emissions and around 11% in building materials and construction.
In a net-zero or net-negative world, we need the majority of the global buildings to turn from being “consumers of energy” into “generators of energy”.
Yes, we need the majority of our buildings to be “energy-positive” buildings. This is to drastically reduce 30% of global energy consumption.
Can buildings be “generators of energy” instead of “consumers of energy”?
Is it possible to create “energy-positive” buildings? Is it possible to make buildings “generators of energy”?
The answer is “Yes”. It is possible. In reality, there are already many “energy-positive” homes and buildings around the world.
Honda Smart Home, California, USA
The 2,421-square-ft (225m2) new residential home, located in the West Village of the University of California, was developed by Honda as a demonstration for future living with renewable energy and electrified vehicles. After starting occupancy in Jan 2014 and from 2014 to 2022, the Honda Smart Home project became a living laboratory that enabled Honda to evaluate the hardware and software of its Honda-designed Home Energy Management System (HEMS) that monitored, controlled, and optimized electrical generation and consumption using the home’s microgrid.
Honda Smart Home is “energy-positive” even after providing electric vehicle charging for its occupants.
The Honda Smart Home website has raw technical data collected from 239 channels that measure power, water, weather, and temperatures during occupancy.
Vali Homes Prototype I in Phoenix, Arizona, USA
The two-bedroom 1,500-square-ft (139m2) new residential prototype home is designed to fit on a typical downtown lot. Starting occupancy in 2013, the house uses about 6,000 kWh of electricity per year offset by an on-site 3.6kW photovoltaic system to be an “energy-positive” house. The design strategy includes reducing energy consumption using tightly sealed building thermal envelope, as well as efficient appliances and mechanical systems such as a heat recovery ventilator that produces 24-hour air exchange.
Both the Honda Smart Home and Vali Homes Prototype I Home have been certified as Zero Energy Building by The International Living Future Institute’s (ILFI) Zero Energy (ZE) certification.
The International Living Future Institute (ILFI)
The International Living Future Institute (ILFI) is an environmental non-governmental organisation (NGO) committed to transforming communities to be socially just, culturally rich, and ecologically restorative.
ILFI operates the Living Building Challenge, which is one of the built environment’s most ambitious performance standards. It is a hub for many other visionary programs that support the transformation toward a living future.
ILFI’s Zero Energy (ZE) certification was created to recognize projects that demonstrate the highest level of energy performance and employ renewable energy resources. To achieve ZE certification, 100% of the building’s energy needs on a net annual basis must be supplied by on-site renewable energy in a 12-month performance period.
At the end of the 12-month performance period, as demonstrated by a utility meter, or where not available a private metre, the total energy generated must be equal to or greater than the total energy consumed.
As of 21 August 2023, 92 buildings of various sizes, types, purposes, uses, and locations around the world have been certified by ILFI to be Zero Energy (ZE) certified buildings.
Another 151 buildings have been registered to be Zero Energy (ZE) certified by ILFI but have not completed the performance demonstration or have not completed the certification process.
Visit International Living Future Institute (ILFI) website for more information about ILFI.
Here are some case examples of the 92 homes and buildings that have been Zero Energy (ZE) certified:
DPR Phoenix Office Building, USA
DPR Construction, a US company, renovated 3 of its regional offices to be “energy-positive”. DPR Phoenix Office Building is a 1,533-square-ft (142m²) renovated building that started occupancy in 2012. The building was originally built in the 1970s. The office building has an open-office environment housing 58 workstations and floater spaces, 9 conference/training/innovation/mediated technology rooms, support spaces, fully-equipped gym/locker facilities, and a zen room for a quiet retreat. The renewable energy systems employed by the DPR Construction Phoenix Regional Office are a 79kW-DC photovoltaic array and a solar thermal hot water system. At the end of the 12-month performance period, the regional office building had a net excess generation of 6,980kWh over and above the consumption.
DPR San Diego Office Building, USA
DPR San Diego Office Building is a 24,144-square-ft (2,243m²) renovated building that started occupancy in May 2010. Like the DPR Phoenix Office Building, DPR wanted to demonstrate that an existing building could be renovated without introducing the embodied energy required for a new construction. The strategy to reduce energy consumption was to capitalize on the climate in the region for the building’s cooling and ventilation requirements. Onsite generation of energy was through a 64kW-AC photovoltaic system.
DPR San Francisco Office Building, USA
DPR San Francisco Office Building is a 20,010-square-ft (1,859m²) renovated building that started occupancy in 2015. The existing building was over 60 years old and underwent a structural upgrade to install a rooftop PV system. The building reduces energy demand through extensive use of daylight, efficient equipment, and an enhanced building thermal envelope.
This was the first “energy-positive” office in the City of San Francisco.
EchoHaven House, Calgary, Canada
This 2,750-square-ft (255m²) new 25-home residential building in Calgary Canada started occupancy in 2018. Solar panels are installed on the fronts and tops of each house and each house is constructed using recycled materials. Although these homes cost 12 to 15% more to build compared to other typical homes, there will be savings from the ongoing utility costs by turning to solar panels as renewable energy sources.
435 Indio Way commercial office building, Silicon Valley, USA
This 31,797-square-ft (2,954m²) commercial office building in Silicon Valley, which started occupancy in 2017, was retrofitted to be net zero energy commercial offices. The design strategies include implementing integrated rooftop photovoltaics, 43 custom skylights, operable electrochromic glass windows, and an upgraded building thermal envelope. Skylights and windows open automatically at night to “flush” the building, while large ceiling fans keep the air gently circulating. During the day the space is 100% naturally lit by skylights and electrochromic windows.
National University of Singapore School of Design and Environment, Singapore
The new 6-storey National University of Singapore School of Design and Environment building is an 8,588m² building that started occupancy in Jan 2019. The building is the first building in Southeast Asia to be awarded the Zero Energy (ZE) Certification by ILFI. Advanced monitoring of occupancy, space usage, indoor air quality, and weather conditions helps optimize system operation. The building’s hybrid cooling system supplies 100% fresh pre-cooled air and combines air-conditioning and fresh air to help reduce energy consumption. Electricity produced by 428kWp 1225-panel rooftop solar system is used to power all systems with any excess exported dynamically to the campus grid for adjacent building usage.
Adlai E. Stevenson High School District 125, USA
This 53,800-square-ft (4,998m²) new school building started occupancy in 2019. The new facility includes world language classrooms, maker labs, and multi-purpose presentation spaces for conferences and extended learning, as well as five advanced physics and engineering program labs.
San Diego East County Office and Archives, USA
The San Diego East County Office and Archives building is a 25,000-square-ft (2,323m²) building that started occupancy in 2020. The building is separated into 15,100 square feet (1,403 m²) of branch office and 9,900 square feet (920 m²) of achieves with over 6,000 square feet (557 m²) of an archive storage area that requires highly protected space to accommodate high levels of temperature and humidity control, along with a focus on security in the event of fire, water, or theft.
Cincinnati District 3 Police Headquarters, USA
Cincinnati District 3 Police Headquarters is a 31,000-square-ft (2,880m²) new building which started occupancy in 2015. This is one of the first 365/24/7 mission-critical zero energy buildings in the USA. A 365/24/7 mission-critical facility means additional operating hours leading to higher energy consumption than a typical building. The building’s 329KW solar photovoltaic power system generates 60% more energy than it consumes.
Illinois Countryside City Hall and Police Headquarters, USA
Illinois Countryside City Hall and Police Headquarters is a new 34,600-square-ft (3,214m²) building that started occupancy in 2019. The L-shaped building is divided into police department functions on the north and city hall functions on the south with a shared public amenity area. A centrally located two-storey lobby is an access point to both the police and city hall. Photovoltaic arrays at the building’s roof and over the police vehicle carport areas provide onsite renewable energy.
Kaiser Santa Rosa Medical Office Building 6, USA
Kaiser Santa Rosa Medical Office Building 6 is an 87,000-square-ft (8,082m²) new building that started occupancy in 2022. This is one of the first medical care centre buildings in the USA that has been awarded the Zero Energy (ZE) certification by ILFI.
King County Parks North Utility Maintenance Facility
King County Parks North Utility Maintenance Facility is a 56,628-square-ft (5,261m²) renovated building that started occupancy in 2006. The utility maintenance facility includes a crew/workshop building and a parking/workshop building. The facility became “energy-positive” following the installation of 2 solar energy systems.
Kohler Environmental Center Choate Rosemary Hall, Wallingford, CT, USA
The new 29,325-square-ft (2,724m²) building started occupancy in August 2012. The academic and residential facility, designed for up to 20 students, includes 14 dormitory rooms, faculty apartments, common spaces, classrooms, laboratories, and a state-of-the-art research greenhouse. 100% of the building’s annual energy needs are provided by a 294-kW roof-mounted solar panel system, and waste cooking oil. Low embodied energy materials such as timber frame structures were used during the construction as much as possible.
Locust Trace AgriScience High School Campus, in Lexington, KY USA
Locust Trace AgriScience High School Campus is a new 69,998-square-ft (6,503m²) facility that started occupancy in 2011. The high school campus includes an academic building, an automated greenhouse, a livestock barn, and an arena on an 82-acre Kentucky countryside land. An integrated design that features an airtight envelope, expanded indoor temperature setpoints in specified areas, a solar thermal system and a geothermal heat pump reduces energy consumption drastically.
Richardsville Elementary School in Bowling Green KY USA
Richardsville Elementary School is a new 72,280-square-ft (6,715m²) building that started occupancy in 2013. This is the first school located in the rural community of Richardsville in Kentucky to be awarded the Zero Energy (ZE) Certification by ILFI. The strategies to reduce energy consumption include orientating the building to harvest natural light thus reducing the use of artificial lighting, using energy-efficient systems, and constructing the building to have a high-performance thermal envelope.
SFO – 1057 – Airfield Operations Facility Owned by San Francisco International Airport, USA
The 20,240-square-ft (1,880m²) renovated airfield operations facility building started occupancy in June 2014. The design allows for a portion of the building to operate 24 hours a day. Each zone has a schedule depending on operations. Occupancy sensors are located in every room and are connected to the lighting control system, which varies the intensity of lights and light switches if needed. A 400-panel 141.4kWh office and garage rooftop solar system that generates excess energy over its usage.
Tilal Al Ghaf Pavilion in Tilal Al Ghaf, Dubai, UAE
The new 3,433-square-ft (319m²) commercial building in Dubai started occupancy in January 2020. The onsite 309kW PV system produced actual energy of 268,160 kWh with an excess of 169,096 kWh more than 50% over the actual energy consumption of 99,064 kWh during its 12-month performance period.
University of Illinois Electrical and Computer Engineering Building, USA
The University of Illinois Electrical and Computer Engineering Building is a 183,020-square-ft (17,003m²) renovated building that started occupancy in 2014. The university building catered for has more than 3,000 students in the department and includes facilities such as labs, classrooms, meeting spaces, and offices. The building’s orientation was chosen to maximize energy efficiency. The building is designed to consume about half the energy of an average new building of the same size and type.
Wilde Lake Middle School in Columbia Maryland, USA
Wilde Lake Middle School is a new 106,622-square-ft (9,905m²) building that started occupancy in 2018 for 800 students and staff. The school is Maryland’s first Zero Energy (ZE) certified school. This was accomplished by the installation of 2,044 solar panels with 663kW capacity on the rooftop of the building and site. Together, they produced an actual energy of 821,618 kWh, 393,317 kWh more than the actual energy consumption of 428,301 kWh during the performance period.
The above homes and buildings are just some of the 92 homes and buildings that have been awarded Zero Energy (ZE) Certification by ILFI.
Besides these 92 homes and buildings, there are 151 other homes and buildings that have registered for Zero Energy (ZE) Certification by ILFI but have not completed the certification process.
As well, there are many more “energy-positive” homes and buildings around the world that are not certified by ILFI or any other certification standards. HouseZero is one of them.
HouseZero – Harvard Center for Green Buildings and Cities (CGBC) Headquarters Building
Opened in Dec 2018, this renovated pre-1940s Harvard CGBC’s “energy-positive” HouseZero Headquarters building uses nearly zero energy for heating and cooling, zero electric lighting during the day, operates with only natural ventilation and produces zero carbon emissions. It is intended to be used as a data-driven living laboratory with nearly 300 sensors producing 17 million data points each day, and with software algorithms automating the opening and closing of windows and circulating air through cross ventilation and convection flows so a comfortable indoor environment – including temperature, humidity and air quality – can be maintained without building heating, ventilation, and air conditioning (HVAC) system. The building interacts with the seasons and the exterior environment more naturally.
When the weather is uncomfortably hot or cold, the house will tap into the ground’s temperature, which is more stable, via a ground-source heat pump that channels naturally heated or cooled water into the building, where it runs through the radiant floor slabs to help regulate temperature.
The power from the roof-top solar system is stored in the basement batteries for use during nighttime and low-sun conditions. The surplus energy is fed back into the grid.
The roof-top solar system produces surplus energy more than the equivalent energy used throughout the intended lifespan of the house including embodied energy for construction materials and building operations for over its estimated 100-year building life.
Read HouseZero updates for the Harvard CGBC HouseZero first-year performance and other updates.
Harvard CGBC’s “energy-positive” HouseZero Headquarter building was built with help from Powerhouse consultants.
Norway’s Powerhouse
Powerhouse is a collaboration consisting of real estate company Entra, Skanska development company, non-profit environmental organization ZERO, architecture firm Snøhetta, aluminium manufacturer Sapa Og, and consulting firm Asplan Viak.
Powerhouse’s mission is to build buildings that provide more power throughout their lifetimes than they cost to build, run, and demolish.
In other words, Powerhouse renovates existing buildings or builds new buildings to be “energy-positive” and “generators of energy”, even after accounting for the energy needed to construct the building right through to the energy needed to demolish the building at the end of their lifespan, assumed to be 60 years.
Visit Powerhouse website for more information about Powerhouse.
Powerhouse Kjorbo Project
Opened in April 2014, Powerhouse Kjørbo consists of 2 renovated 1980s office buildings with a total floor area of 5,200 m2 in Sandvika outside of Oslo, Norway.
By optimising and combining known technologies in new ways, these office buildings’ energy consumption has been reduced by more than 86% through efficient ventilation, insulation, and lightning. Energy wells just outside the buildings are linked to a heat pump for space ventilation and hot water heating. The wells are used for free cooling during hot periods in the summer. The heating and cooling systems are programmed to only be used when needed, the number of sensors and control units is limited to a minimum. Warm and cold air is drawn in naturally to regulate the temperature inside the building.
As well, recycled resources and materials are used throughout the building.
The buildings’ rooftop solar system produces around 200,000 kWh/year. Electricity needed for ventilation, lights, heating, and cooling is 100,000 kWh/year which gives a surplus production of energy. Surplus energy is being used in the nearby hydrogen refuelling station.
Powerhouse Kjorbo is a fine example that buildings, not just new buildings but also renovated buildings, can be “generators of energy” rather than “consumers of energy” through smart design and smart use of technologies.
Even buildings located as far north as Norway can be “energy-positive”.
Powerhouse Drøbak Montessori School Project
The Montessori School is a new secondary school that houses about 60 students and 15 teachers. The “energy-positive” school was commissioned in 2015.
The solutions for heating, cooling, and ventilation are based on the principles used at Powerhouse Kjørbo with further improvement and optimisation. The school consumes only about 25% of the energy required for similar-size schools.
The building produces about 30,500 kWh with a roof-top solar system orientated directly towards the south with a 33-degree incline and a ground source heat pump system.
Powerhouse Brattorkaia Project
Powerhouse Brattorkaia Project is an 8-storey office building with a floor area of 18,200 m2 including a mezzanine floor and underground parking in Trondheim, Norway.
Like other Powerhouse projects, Powerhouse Brattorkaia generates more energy in its operational phase than it consumes for the production of building materials, construction, operation, and disposal of the building.
The building’s site was chosen to have maximum sun exposure. Its roof and the upper part of the façade are installed with about 3,000 m2 of solar panels to harvest as much solar energy as possible. The building produces about 500,000 kWh of renewable energy annually.
The building is well insulated with excellent ventilation such that there is limited need for heating. Being close to the sea, seawater is used for heating and cooling. Daylight conditions are optimized throughout the building so artificial light use is kept at a minimum. Only energy-efficient electrical appliances are used in the building.
As a result, Powerhouse Brattørkaia consumes only about half the amount of energy for lighting than a typical similar-size commercial office building.
On average, Powerhouse Brattørkaia produces 2 times the amount of electricity it consumes daily. The surplus electricity is supplied to its neighbouring buildings, electric buses, cars, and boats through a local microgrid.
In addition, the building is designed to store surplus energy in the summer months for use in the winter months when daylight is at a minimum.
Hotel Svart Project
The 94-room Six Senses Svart Hotel, planned to be open in 2024, is Powerhouse’s next most challenging project, aiming to be the world’s first “energy-positive” hotel.
The hotel is located above the waters of the Holandsfjorden fjord in Norway at the base of the Svartisen glacier, the second-largest glacier in Norway.
Employing technologies, innovations, and learnings from Powerhouse’s previous projects, the Hotel Svart Project is designed to have minimum impact on both the land and the waters. The design adopts the highest energy efficiency standard, optimizes natural light and heat, and consumes 85% less energy compared to other similar-size traditional hotels.
The glass-front circular building sits on poles above the waters of the Holandsfjorden fjord offering hotel guests a panoramic view of the surrounding. The hotel will have an indoor-outdoor spa, 4 restaurants, and 2 electric boats for guest transfers and offer hotel guests activities such as ice climbing on the glacier, yoga in the midnight sun, wildlife spotting, diving, and fishing.
The building will harvest enough solar energy to cover the hotel and its amenities operations, including the 2 electric boats used for guest shuttles, and the energy needed to construct the building. Organic materials are used extensively for hotel construction to minimise embedded energy.
The hotel aims to be fully off-grid, carbon neutral, and zero waste by 2030 with total self-sufficiency in energy and all utilities such as water and waste.
The Hotel Svart Project will inspire future sustainable innovations in the hospitality industry.
All these Powerhouse “energy-positive” buildings not only focus on the daily operation of the buildings but also drastically reduce the energy consumed during construction and in the future demolition of these buildings.
The embodied energy, which is the energy required for extracting, processing, manufacturing, and delivering the building materials for construction, is reduced to a minimum in all Powerhouse projects.
In a nutshell, “energy-positive” buildings can achieve “energy-positive” by:
(1) Lowering embodied energy for the building construction;
(2) Reducing energy for daily operations drastically;
(3) Harnessing renewable energy for daily operations of these buildings.
Passive House buildings
Passive House buildings focus on drastically reducing energy consumption for daily operations.
The concept of Passive House building was developed by the Passive House Institute (PHI), which was founded back in 1996 by Dr Wolfgang Feist.
Recognising that the majority of energy needs come from heating and cooling demand, Passive House buildings work based on 5 principles:
(1) Have an airtight building envelope such that the internal environment within the building can be fully controlled;
(2) Have sufficient thermal insulation within the building’s envelope to provide thermal separation between the heated or cooled conditioned inside environment and the outdoors;
(3) Incorporate a mechanical ventilation unit to filter the air entering into the building;
(4) Orientate high-performance double-glazed windows to let solar radiation penetrate through during winter but not too much during summer; and
(5) Use less heat-conducting materials to ensure continuous insulation between the building interior and exterior.
By following these 5 principles, a Passive House building can adapt to different climates around the world, and make efficient use of the sun, internal heat sources, and heat recovery, rendering conventional heating systems unnecessary even in winter.
Ventilation is achieved with the help of a Mechanical Ventilation Heat Recovery (MVHR) unit. The unit removes heat from exhaust air and uses it to heat incoming air to maintain a stable indoor temperature.
During warmer months, Passive House buildings make use of passive cooling techniques such as strategic shading to keep comfortably cool.
Passive House buildings consume up to 90% less energy for heating and up to 80% less energy for cooling than typical buildings, depending on climate.
Although an extra cost of 10-20% more is expected to build a Passive House building, the extra cost could be offset by a reduction in operating energy bills.
As of July 2023, over 39,600 homes and buildings of a wide range of sizes, types, purposes, uses and locations are certified according to the strict Passive House Institute certification criteria. These 39,600 buildings represent a total floor area of 3,660,000 m².
These 39,600 Passive House homes and buildings, if not already “energy-positive”, could become “energy-positive” by installing an onsite rooftop solar system and/or other renewable energy sources sufficient to more than offset the low energy consumption.
Therefore, if it is feasible to install a renewable energy generator such as a roof-top solar system on the building, an energy-efficient Passive House building can become “energy-positive”.
Visit Passive House website for more information about Passive House buildings.
Some of these 39,600 Passive House homes and buildings are listed below:
Read more about Passive House certification worldwide and the database on the International Passive House Association (iPHA) website.
World Green Building Council
The World Green Building Council (WorldGBC), with its international network of more than 75 Green Building Councils in countries around the world, is promoting the resource-efficient solutions and accelerating the actions to decarbonise built environments around the world through coordinated effort of these countries’ Green Building Councils.
With their efforts, there will be more and more “energy-positive” buildings – new or renovated.
Check out the World Green Building Council (WorldGBC) website for more case examples.
“Energy-positive” Buildings will be the norm for future buildings
The technologies and technical solutions are available to build new buildings or renovate existing buildings to be “energy-positive”, as demonstrated in all the case examples.
I am optimistic that “energy-positive” buildings and buildings that are “generators of energy” will be the norm in the not-too-far future!
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