A Zondits Interview: Integrating Geothermal Heat Pumps with Conventional Building Systems

Process Efficiency

Zondits Interview with Greensleeves, LLC

Valerie Eacret for Zondits, February 27, 2014

Greensleeves, LLC created software that was used in a system design that won the 2014 ASHRAE Global First Place Technology Award for Educational Institutions—New Construction. That design reduced the heating and cooling energy use by 57% for a laboratory/classroom at The University of Findlay in Findlay, OH. This system earns the school a 65% annual return on its energy efficiency investment. In the case of a hospital, this system optimization technology reduced the capital cost for their geothermal HVAC system by a third ($500K).

W. Michael Linn, President & CEO of Greensleeves, LLC

Zondits reached out to Greensleeves and asked their President and CEO, W. Michael Linn, to speak about geothermal systems in general, and more specifically about using Greensleeves’ patent-pending software to control hybrid geothermal heat pump systems.

Z: Congratulations on your ASHRAE award – very impressive. Let’s start with the big picture: What do you see as the main problems with conventional HVAC systems?

GS: Over 70% of U.S. electricity is generated by burning coal, petroleum or natural gas. This is a poor approach from the point of basic physics. Fossil fuels are burned to produce thermal energy, convert that to electrical energy, transport that long distances [and] then reconvert it into thermal energy. These losses are roughly twice the size of actual purchases, making electricity the largest buildings energy source in “primary” terms (including conversion and transportation losses) at about 72%. Greensleeves technology cost-effectively harvests energy from the environment locally and uses it directly. There is a minimum of transportation and conversion, making the system much more efficient, and the physics can’t be matched with imported energy.

Z: Geothermal heat pump systems have been popular in Europe for many years and are only recently drawing attention in the US. Why is that?

GS: They constitute 84% of the HVAC systems in Sweden, for example, because they use approximately 33% less energy. The barrier to adoption in the US (and globally) is that they cost about 30% more because the system requires a geothermal heat exchanger, or GHX (think of this as a radiator built underground).

Z: Beyond the cost/benefit side of things, what are common difficulties you find in getting these systems installed in the US?

GS: Lack of design and construction expertise is a real issue. You still need to find a specialist to do the work – and this will be the case until these systems are more mainstream. There is also a significant problem in customizing the controls of the building to the individual design of the building. The installation rarely matches the design.

Z: How can these difficulties be addressed?

GS: Greensleeves provides design optimization software to simplify the process. In a patent-pending process, the engineer’s design will go directly into Greensleeves optimization engine and produce the lowest capital cost design for the highest energy efficiency. In turn, that automatically produces the control software for that design. Those controls are subsequently installed in the building – [there’s] no human intervention. Also, the GeoModule measures the actual building load and performance, allowing the design to be compared to performance, and allowing the building to be tuned to maximize the performance. It also allows a timely comparison of the “as constructed” system to the “as designed” system. While this sounds simple, current technology never compares the building performance to actual. This reduces the risk for the building owner and makes the performance of the system immediately and scientifically clear.

Z: Given all of that, why do you think these systems should prevail in the US?

GS: Geothermal is the most energy-efficient way to cool and heat a building today. The government recognizes this and offers tax incentives. However, there is still a cost premium due to the expense of the GHX. The GeoModule™ reduces the GHX but still qualifies for tax incentives. This will make geothermal not only energy-efficient but also cost-effective.

Z: Moving to the Greensleeves technology, please describe the systems that utilize your software.

GS: The GeoModule provides intelligent energy management that controls the thermal exchange in the geothermal borefield and optimizes the acquisition, storage, transportation and utilization of energy through the system. It converts a conventional geothermal system into a thermal battery allowing the system to capture heat at the hottest part of the day, or season, and use that heat at the coldest part of the night, or season, and the process is reversed for cooling. Up to 75% of the energy required to heat and cool buildings can be harvested and used directly from the environment, and even more can come from recycled energy.

Z: What advantages does the GeoModule provide these systems?

GS: Greensleeves technology reduces the size of the GHX by more than 50%. But the technology also allows the system to recycle waste energy, further increasing the energy efficiency.

It reduces the capital cost, increases the energy efficiency compared to comparable conventional systems, and makes it easier to design, install, and control. It also reduces the cost and risk of maintenance.

Z: How does the efficiency of these systems compare to conventional geothermal systems?

GS: Even when used with the high-efficiency geothermal systems being installed today with variable refrigerant flow, efficiency is improved by about 20%. It also gets rid of the noise, space and maintenance problems required by the condenser units for those systems.

Z: Where are these systems most applicable and where are they not applicable, especially in terms of climate, geography and building type?

GS: By providing the ability to time-shift cooling to the night (3× more efficient) and to the winter (11× more efficient), this can be used in all climates. The GeoModule has now been sold for use in all high-occupancy building types, including higher education, office buildings and hospitals. In urban areas, the question is where and how to install the geothermal heat exchanger. Greensleeves works with cities to radically reduce the size of the geothermal exchanger as well as the water use. One 110,000 sq ft office building in Florida uses 2 million gallons of potable water a year for cooling. The GeoModule cuts that to 60K gallons.

Z: We know that borefields (GHX) can be a challenge. Please discuss the pros and cons of horizontal, vertical and sloped geothermal boreholes?

GS: The GeoModule allows the designer to freely mix any of these types of loops with geothermal pipes put under water in lakes, rivers, etc. This lets the designer use the cheapest locations first, then add capacity from other sources. This takes advantage of local land features like lakes, rivers, parking lots, etc. Different types of boreholes are used to fit specific land constraints. Horizontal takes much more land, but that may be cheaply available during site prep when parking lots are being built. Sloped are generally used to get under things (e.g., forests, buildings, etc.). Vertical takes the least land and can be put under buildings, parking lots, and so on. Vertical is often more efficient.

Z: What tax benefits and incentives are available?

GS: There is a direct IRS credit of 10% and MACRS (accelerated) depreciation over 5 years, rather than the 39-year depreciation for conventional systems. For the 35% tax bracket, this is equivalent to a 43% reduction in the cost of the entire HVAC system.

Z: So often it comes down to final cost. What is the bottom line for choosing between these systems and conventional technology?

GS: For a taxpayer a geothermal installation using our technology generally costs 10%–22% less to build and install, and for a non-taxpayer this costs generally 10%–20% more to buy. The energy efficiency is generally 50% more and maintenance runs $.05 to $.10 less per sq ft per year to maintain. This also eliminates the risk that the system will lose efficiency over time.

The optimization software dashboard shows energy savings for a hybrid geothermal system. It compares the energy use of the installed system to the energy use of the alternative conventional system under current operating conditions in real time.

About Greensleeves  

Greensleeves LLC was created to make alternative energy affordable for powering buildings – to make clean energy systems cost-competitive with conventional HVAC systems.  The company invests in designing and marketing systems that use advanced energy modeling, mechanical engineering and computer technology to deliver a new type of local energy management equipment. Greensleeves has patents pending on technology capable of predicting and optimizing energy demand and supply, selecting the best energy source, and using thermal storage to collect and store energy when it is available for future use when it is needed.  These capabilities are prepackaged by Greensleeves into hybrid-ready systems preconfigured to use multiple heating, cooling, and storage devices working together – for example, a geothermal system supplemented with a cooling tower. These optimized hybrid systems allow engineers to design clean energy-powered systems that are less expensive to buy and operate, faster to design and build, and easier to use.  Greensleeves has specifically targeted the rapidly growing geothermal market with its GeoModule™ family of products.

Source: www.greensleevesllc.com


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