Net Zero Buildings Be a Resource By John Mesenbrink
COMMON DEFINITION — U.S. Dept. of Energy Prepared for the U.S. Department of Energy by the National Institute of Building Sciences
“Net Zero requires a quantum shift in thinking where we ‘change the calculus’ in the way we view buildings.” — Ralph DiNola, Executive Director, New Buildings Institute
New Buildings Institute • Verified Zero Energy Buildings — Those with greatly reduced energy loads that have been documented to have met, over the course of a year, all net energy use through onsite renewable sources of energy. • As of 2015 — 39 verified zero energy buildings; 152 emerging zero energy buildings.
Net Energy Use Intensity (EUI) According to ENERGY STAR, EUI is expressed as energy per square foot per year. It’s calculated by dividing the total energy consumed by the building in one year (measured in kBtu) by the total gross floor area of the building. A school contains a main floor consisting of 15,000 square feet, a second floor consisting of 10,500 square feet. The school used 1,170,000 kilowatt- hours of power during the year in question. Kilowatt-hours is multiplied by 3.412 to obtain kBTUs, therefore 1,170,000 * 3.412 = 3,992,040 kBTUs. This is divided by the total square footage of 25,500 square feet for an Energy Use Intensity of 3,992,040 / 22,500 = 156.5 kBTU/sf. Source: arch toolbox
The lower the EUI, the better! Of the 39 buildings verified net zero in 2015, the average EUI is 21.29. The average site renewable EUI offsets the total building actual EUI.
Reduction of EUI Ensuring proper of equipment to improve operational efficiency Installing occupancy sensors Incorporate the use of natural sunlight Provide a means for passive heating and cooling Develop onsite renewable energy generation
Say What? How do we get there? Solar Heating — PV & DHW Wind Power Cogeneration Passive HVAC; geothermal; heat reclamation Low flow plumbing fixtures Rainwater harvesting; stormwater management Greywater Lighting Controls & Sensors; Daylighting District Approach
Bullitt Center, Seattle
Living Building Challenge
Ground-source heat pump and in-floor radiant system heat the building extremely efficiently. • Heat pump converts 53° water from underground tubes to 95° for heating the building. • Heat pump uses a compressor to extract heat and increase temperature in the radiant heat system.
Extremely low-flow toilets reduce water use Toilets use only two tablespoons of water mixed with biodegradable soap to foam the bowl. Toilets and urinals return air to the aerobic composters . The Bullitt Center is the tallest building ever to implement a composting system. These aerobic systems have become very popular in one- story buildings and in places that don’t have access to sewer lines. The challenge was to develop a delivery system from the higher floors that would safely bring the waste down to the composters, while not overwhelming the composters with liquids. When the toilets sense a user, they begin to emit foam. This foam, consisting of a biodegradable soap-like substance and about 3 tablespoons of water, slides down the vertical tubes, creating a low- friction lining to ensure all the waste makes the journey down to the composters.
The world’s only six -story composting toilet system Human waste is transferred to composters and periodically taken offsite to be used as fertilizer. Aerobic digestion heats material to 190 degrees and converts solid waste to compost. When nature calls at the Bullitt Center, you may be surprised to see waterless toilets. Instead of the normal fish bowl, the toilets at the Bullitt center are a specially designed waterless vessel that feeds into the basement composters through nearly completely vertical pipes.
Wastewater Use The project reconnects the hydrologic cycle by infiltrating clean water back into the ground. Water from sinks and showers is stored in a greywater tank and cleaned in a constructed wetland. Clean greywater is infiltrated back into the soil to recharge the local aquifer. Water and biodegradable soap used in the taps and showers drains into a 500-gallon storage tank in the basement of the building. From here, 500 gallons-per-day can be pumped up to the third-floor constructed wetland.
Rainwater harvesting The building will restore the historical relationship of water to the land by collecting rain, returning it to the earth and the atmosphere. The Bullitt Center is designed to help restore the ecological processes of the site back to they way they functioned hundreds of years ago when it was a Douglas fir forest. Below the solar panels, a parapet roof captures rainwater and brings it to downspouts that carry the water to a 56,000-gallon, concrete cistern in the basement. On its way down, the water is funneled through a vortex filter, which removes large particulates. Next to the cistern is a “day - use tank” that holds 500 gallons of clean, potable water. To create the potable water, the rainwater is “ultra - filtered” through three ceramic filters, with the finest removing viruses. The rainwater is also passed under ultraviolet light and through activated charcoal and a small amount of chlorine is added. While chlorine is a toxic chemical, research showed examples of people getting sick from bacterial growth on faucet heads, so the team decided to use a small amount of chlorine – then remove it at the faucet head with activated charcoal – to protect public health.
Solar District
DPR Construction, Phoenix
Before…
After…
“When we started our project people were thinking, ‘Passive cooling in the desert, really?’” — Dave Elrod, DPR Construction’s regional manager.
Natural Ventilation At the core of the building’s natural ventilation program is a system of operable windows and custom- made “shower towers,” which draw cool air in and through the open floor plan, with the aid of large ceiling fans. Capped with showerheads to mist and cool the air entering the building, the shower towers, which are ganged together with a sump pump, recirculate domestic cold water. The hot air is then expelled through a large solar chimney.
Bridgewater State University — George A. Weygand Hall Bridgewater, Mass. * Fully vetted net zero ready design
Shower drain heat recovery
Lehman College Science Hall
Stormwater & Greywater Science Hall at Lehman College implements an aggressive stormwater and greywater management system and includes provisions for future blackwater treatment. Not only does the engineered wetland in the building’s courtyard treat black and greywater, the staff and students use it to aid in their research.
Phipps Conservatory — Pittsburgh, Pa.
Center for Sustainable Landscapes The Center for Sustainable Landscapes is a $15 million, 24,350-square-foot, off-the-grid office building and educational center on the grounds of Phipps Conservatory and Botanical Gardens in Pittsburgh. The recently opened center boasts an impressive combination of the latest green building technologies to achieve net-zero energy use. It has on-site lagoons and wetlands to process rainwater and greywater, a photovoltaic solar energy harvesting system, and its M/E/P design reduces energy usage by an estimated 50% mostly through passive energy systems, natural ventilation including underfloor air distribution, whole-building daylighting and a native-plant green roof.
Green Roof
Rainwater Harvesting • 2.9-acre project site is net zero water, managing all rainfall and treating all sanitary waste on site • Site can manage a 10- year storm event (3.3” of rain in 24 hours) • A full ½ acre of rooftop runoff – approximately 500,000 gallons – is harvested from upper campus glass roofs and lower site • Stored in a 60,000-gallon underground rain tank • Rainwater is used for toilet flushing, as well as interior irrigation and maintenance as required • Ultralow flow plumbing fixtures include waterless urinals and dual-flush toilets for water conservation • Harvested water is reused to offset conservatory irrigation needs, greatly reducing impact on municipal sewage treatment and energy-intensive potable water systems
Lagoon System Captures stormwater runoff from portions of the site and the Tropical Forest Conservatory roof Replicates natural water treatment process that occurs in wetlands and marshes Water flows through fountains and a lagoon where plants and their symbiotic root microbes absorb organic and mineral nutrients Water is processed to tertiary non- potable standards Post-treatment water that overflows the lagoon flows into underground rain tank storage
Norton Commons’ North Village North Village development will become the largest 100% geothermal residential community in the U.S. to date.
Random Thoughts Cost — One of the biggest prohibitive factors Size — A majority of these projects are smaller in scale Payback — How do you justify? The same old, same old thinking — Bu-bye Work as a TEAM! — Design team needs to work together and that includes YOU!
Payback
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