Geothermal: digging deep for efficient energy: find out what makes geothermal attractive to FMs and where it's already in use.
In addition to its geothermal capabilities, the Commonwealth Building was ahead of its time in including features like double glazing, heat recovery from ventilation exhaust air and aluminum sheathing. While the 15-story, 215,000-square-foot office building stands today, the geothermal system was decommissioned in 1992. The building is designated as a National Historic Mechanical Engineering Landmark by ASME and is on the National Register of Historic Places for its notable achievement in geothermal history.
Despite being a relic of sorts, the Commonwealth Building is nevertheless remembered for ushering in a new era of sustainable facilities, as the number of geothermal applications has increased, as 50,000 geothermal heat pumps are installed in the U.S. each year. But with all of the other sustainable energy solutions out there, what is so appealing about geothermal energy?
Perhaps most importantly, geothermal provides steady ROI and savings on energy spend. Energy generation is one way geothermal can make an impact on a facility. In especially rich geothermal areas, water found below the Earth's surface can be hot enough to turn steam turbines in electric generators. Some facilities have adopted systems like these to achieve net zero status.
Also, with HVAC consuming 44% of the energy in commercial buildings, geothermal heat pumps provide a cost-saving alternative. Geothermal heat pumps can heat and cool buildings with very low electricity demand and can reduce emissions, returning costs to users in 5-10 years.
Not only is it a more efficient energy source, but geothermal is also versatile. Many renewable energy sources require specific climate conditions, but geothermal can be installed in nearly any climate. As the DOE explains, "Ground temperature is warmer than the air above it during the winter and cooler than the air in the summer. The geothermal heat pump takes advantage of this by exchanging heat with the earth through a ground heat exchanger." Thus, geothermal can stabilize air temperature in a building because of its consistency.
Unlike other energy sources, geothermal does not rely on any finite quantity of resources--it merely requires the Earth's interior to maintain its temperature as it's done for billions of years. Furthermore, the reliability of geothermal systems themselves provide stability. The low-maintenance system has a 50-year life span for ground loops and 20 years and up for pumps and compressors.
Reliability extends beyond simply the physical nature of geothermal. Energy costs after installation stay steady, which provide a distinct advantage over other renewable energy sources because that considerably reduces price volatility.
Those who invest in geothermal are not at the same mercy of price spikes and energy crises as those who invest in other energy systems--renewable or otherwise.
After the installation of a system, geothermal solutions do not take up much space because the system works underground. Therefore, you can easily cover it, which can save space and give aesthetic freedom to design above the system.
Moreover, heat pumps are versatile and allow more options for installation. "Geothermal heat pumps circulate water or other liquids through pipes buried in a continuous loop, either horizontally or vertically, under a landscaped area, parking lot or any number of areas around the building," says the Geothermal Energy Association.
Of course, as with any technology, geothermal has its limitations. The capital required to install a system can be higher than many FMs can even consider managing. However, it is mostly a one-time investment that pays dividends through its expected energy savings. Either way, it is a major decision to make for a facility.
To sway that decision towards the more affirmative option, the federal government has implemented a series of programs and incentives for installation. In addition to tax breaks that have aided those looking towards renewable energy like geothermal, projects like the Small Business Vouchers Pilot provide businesses with more opportunity for renewable energy, including geothermal.
However, researchers at the Insitute of Political Economy at Utah State University point to indicators outside of government programs, tax breaks and policies to predict the future of geothermal applications.
"Although policymakers favor geothermal power through mandates and subsidies, markets, not government policies, are best equipped to determine the true economic viability of geothermal power," the researchers explain.
"New technology and increased market demand will likely decrease the need for subsidies and make geothermal more economically viable," explain the researchers. As geothermal systems increase to the tune of 50,000 per year, the feasibility of more affordable implementation might also increase.
Whether you are ready for geothermal now or are considering it for the future, the nine geothermal projects presented in this issue range widely in their applications. These projects all exemplify innovation in geothermal and have paid dividends for their facilities with this clean power source.
THE MONTREAL BIOSPHERE
Montreal's Biosphere is an interactive museum dedicated to environmental awareness. Due to its unique architecture, energy consumption is substantial for this 48,437-square-foot geodesic dome.
Two pumps were placed just under 300 feet deep and provide 1,757 MWh of energy per year. The installation cost $525,000 Canadian in 1998 and the payback period was under six months.
The geothermal system, combined with other efficiency strategies like solar and wind, has reduced energy usage by 459 MWh annually over a conventional electrical HVAC option.
With a facade that's over 40% windows and a location in a cool climate zone, this 21% decrease supports sustainable mission of the only environmental museum in North America.
CENTER FOR ARCHITECTURE
NEW YORK, NY
Think geothermal can't work for an urban site? The Center for Architecture, located in the Greenwich Village neighborhood of Manhattan, proves a loop field can hide beneath a busy borough.
Installed in 2003 during a renovation, a geothermal heat pump system draws groundwater from two 1,260-foot-deep wells that were drilled through the sidewalk at the headquarters of the AIA New York Chapter. It provides heating and cooling for the 15,000-square-foot building, which is comprised of offices and open spaces.
The geothermal system itself cost $100,000, which was largely offset by a grant from NY5ERDA, and had a payback period of three years. It is one of the first installations in New York City.
STATUE OF LIBERTY RETAIL PAVILION
LIBERTY ISLAND, NY
Lady Liberty has a surprising feature underneath her feet --clean energy from ground source heat pumps. The 6,600-square-foot Liberty Gift Pavilion (shown at far left) that greets visitors to the famous statue was renovated in 2010 with sustainability in mind. Drawn from 55-degree well water over 1,500 feet below, water is pumped at a rate of roughly 120 gallons per minute to heat and cool the facility. Drilling took five days and minimally impacted foot traffic.
The geothermal system has secured a 35% savings in energy. The well field also eliminated the need for large exterior units, reducing the building's footprint. The system helped the pavilion, which is owned and operated by Evelyn Hill Inc., earn LEED Platinum for New Construction.
COLORADO CAPITOL BUILDING
The Colorado State Capitol is the first state capitol building to be cooled by ground source heat pumps. The system was added in 2013 as part of a larger energy performance contract covering all 19 of the Capitol's buildings. It uses an open-loop two-well system at a depth of 850 feet, which supplies constant 65-degree aquifer water.
The installation replaced HVAC equipment that was "anywhere from 25 to 70 years old without affecting existing ductwork," and the system "reduces the main chiller loop load by approximately 200 tons per year," notes the Colorado Department of Personnel and Administration.
The $6.6 million project was offset by a $4.4 million DOE grant and a 15-year lease-purchase contract based on avoided costs. According to the Denver Post, the system "will save an estimated $100,000 in heating and cooling costs in the first year. The savings should escalate each following year by 3%." Colorado's capitol remains the only one to earn LEED EB O&M certification.
IDAHO CAPITOL BUILDING
Idaho has the only capitol building in the U.S. that is heated by geothermal hot springs. This thermal energy system uses steam from a hot water source 3,000 feet underground.
Boise has four independent geothermal heating districts that support 5 million square feet of government, commercial and residential space. According to the Boise Public Works Department, "The city system, which serves 86 buildings, is the largest direct-use geothermal heating system in the U.S." The State of Idaho oversees the system that heats the capitol and several additional facilities along the mall.
Seven geothermal fields are tucked under the stately campus of Harvard University. The institution has a 2016 goal to reduce absolute greenhouse gas emissions by 30% from a 2006 baseline. Geothermal is one of several key strategies to satisfy energy demands while continuing to shrink Harvard's carbon footprint.
"Harvard actively invests in the transition to renewable and alternative energy sources as part of our aggressive climate goal," explains Heather Henriksen, Director of the Office for Sustainability. "Geothermal, in addition to on-site solar and cogeneration, are opportunities to accelerate the progression to clean energy."
"As the university continues to grow, geothermal can be an attractive alternative where extension of the district energy system may be cost-prohibitive," according to Jeffrey Smith, Director of Facilities Maintenance Operations for Harvard University Campus Services. "The environmental benefits and aesthetic profile of geothermal offers an attractive alternative to conventional cooling towers." Switching to geothermal also minimizes HVAC equipment clutter and mechanical noise on campus, adds Lester Gerry, Director of Facilities Management at the Harvard Radcliffe Institute for Advanced Study.
As the urban campus is densely populated with structures, most of Harvard's geothermal installations use open loops. One of the largest fields, the Radcliffe system, was installed in 2006. Five additional wells were added in 2009 to serve Byerly Hall and eventually Fay House in 2012.
"An interconnecting chilled water loop was installed in 2014, allowing all main buildings on Radcliffe's campus to use geothermal. This one field serves approximately 220,000 square feet of space, and energy consumption for heating and cooling is down over 60%," explains Gerry. "We continue to maximize the geothermal efficiency by using the heating side well water in the winter for archival vault cooling. This saves energy on direct expansion (DX) cooling and aids the wells by adding heat energy."
The sole closed-loop system serves the Arnold Arboretum (image on the left) and Weld Hill Research Center, where there was enough space to install the system. It has 88 vertical wells that are 500 feet deep and 11 heat pumps of 35 tons each. As greenhouses have significant cooling demands and laboratories require additional ventilation, geothermal minimizes the site's energy profile.
The fields also serve as a living lab for engineering students. For example, a team of engineering undergraduates from the John A. Paulson School of Engineering and Applied Sciences ran an analysis on the Byerly system to see if it could support an additional load from the adjacent Fay House without losing any efficiencies. Their modeling determined that the Fay House could replace its conventional HVAC units without having to drill new wells just by adding three pumps.
Geothermal has also provided the university with valuable O&M learning opportunities, particularly as the school handled the system design. Several installations have required additional equipment purchases and reengineering to fine-tune performance. "Rather than see these redesigns as setbacks, the university transparently discusses these challenges so others can learn from our findings," notes Smith.
The Bullitt Center employs GSHP systems as one of its strategies to achieve net-zero energy. In pursuit of the Living Building Challenge, the property elected to use a geothermal system to avoid fossil fuels.
Due to the site's compact footprint, three closed-loop fields were drilled to a depth of over 400 feet. Additional wells were also installed as a redundant feature to protect performance if maintenance issues arise.
"Three pumps heat or cool the water circulated through the floor slabs, a fourth sends its loop of heated or cooled water to condition the outside air passing through the rooftop heat recovery ventilator and a fifth is used exclusively to heat water," explains Nina Smith-Gardiner, Principal with 8484 Architecture.
According to the 2012 CBECS data, nearly 50% of commercial buildings are 50,000 square feet or less. "For this size, geothermal is a no-brainer. Particularly if you are using on-site renewables, it makes enormous sense," says Denis Hayes, President and CEO of the Bullitt Foundation.
"The energy used to power the ground source heat pumps is generated on-site, so no fuels have to be purchased, transported and burned at the site. No waste products are created and nothing requires disposal," notes Smith-Gardiner. "The system is highly energy efficient, helping the Bullitt Center to meet its energy needs using only a small fraction (less than 5%) of the energy produced by the photovoltaic panels."
"Keep in mind that 2015 was the hottest summer on record in Seattle, yet we don't have air conditioning other than geothermal," Hayes adds. "This technology enables the Bullitt Center to keep everyone comfortable with as little outlay of commercial energy as possible."
GALT HOUSE HOTEL
The Galt House Hotel is located in the heart of Louisville and the complex boasts one of the largest geothermal heating and air conditioning systems in the world at 4,700 tons. Its 750,000-square foot SUITE Tower opened in 1985 with a 1,700-ton GSHP system. In 1994, the adjacent Waterfront Office Building was built and draws from nearly 3,000 tons of GSHP capacity for its 960,000 square feet.
The east tower's energy cost is approximately 53% lower than its twin tower, which only has heat pumps on the first three floors and serves the remainder with electric heat from air units and package air conditioning units with electric heat.
The heat pumps also saved 25,000 square feet in the SUITE Tower's original design, which otherwise would have been used for maintenance rooms and a 4,000-ton cooling tower.
Renovated in 2008, the ASHRAE Headquarters is a testing ground for HVAC technology. The building features three separate systems: ground source heat pumps, variable refrigerant flow and a dedicated outdoor air system. The geothermal system supports heating and cooling needs on the second floor, spanning 15,290 square feet of office space and 14 zones.
The ground loop has a cooling capacity of 31.5 tons (111 kW). It connects to "14 individual water-to-air heat pumps, six 2-ton units and six 3-ton units. The heat pumps have variable speed fans that are driven with electronically commutated motors with three selected speeds," according to ASHRAE.
As a living laboratory, researchers are drawing data from hundreds of sensors to monitor performance. The GSHP system already collects flow rate, ground loop supply and return water temperatures.
TYPES OF GEOTHERMAL HEAT PUMPS
Based on your location and building's property, you will need a specific type of geothermal heat pump system. They are classified into three main categories:
Closed-loop systems typically circulate an antifreeze solution through a closed loop often made of plastic tubing that is buried underground or submerged in water. The system exchanges heat between the heat pump's refrigerant and the antifreeze solution in the closed loop. Loops can be oriented horizontally, vertically, or in a pond or lake, but vertical is most commonly used in commercial buildings, schools and other larger facilities because it can be implemented in locations with land area restraints.
Open-loop systems use well or surface body water as the conduit for heat exchange to circulate through the system. Once the water is cycled through the system, the water returns to the ground through the well, a recharge well or surface discharge. Open-loop systems only work where there is a ready supply of clean water and the system meets groundwater discharge codes and regulations.
Hybrid systems will use multiple geothermal resources or a geothermal resource with outdoor air through the use of a cooling tower, for example. These systems are most effective when a building needs more cooling power than heating.
Jennie Morton is a contributing editor for BUILDINGS. Justin Feit email@example.com is assistant editor of BUILDINGS.
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|Date:||Nov 1, 2016|
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