Sunday, July 28, 2013


Geothermal Exchange heating and cooling systems or Ground Source Heat Pumps capture energy from the ground - but from where does that energy come?  ... the sun!!    And it's capturing Massachusetts State Legislature attention.

Geothermal exhange systems (GSHP) are increasingly viewed as the missing link to net zero building and energy retrofitting.  When combined with Solar PV, and quality insulation, a geothermal exange system can effectively enable a net zero building or home

The energy captured by thermal exchange is in fact solar energy stored in the earth's crust.  The solar energy is aborbed and maintained at 50-55deg due to the constant rotating and orbital motion of the earth in relationship to the sun.  Water is used to indirectly capture the sun's abundant energy. 

The advantage of this technology is that it is present and available day or night, rain or shine, and regardless of the seasonal impact on direct solar energy technologies (Solar PV, Solar Thermal, etc.).  The key to optimal operational efficiency with these systems is installation design and capabilities.

These systems are not only extremely efficient they are quiet and produce no carbon monoxide.  It's truly wonderful to see this technology added to the mix of available clean, zero carbon energy solutions for business and residential applications ...

Sunday, April 7, 2013


We've been asked if there is a building or home size that's better suited for geothermal applications. The answer is ... not really ... or perhaps better stated ... it shouldn't matter.  If a building, regardless of size, is well constructed and insulated, a well-designed geothermal system is the best choice above all others for long-life and lower operating costs.

Multiple Government Buildings on Large Closed Loop System

Building size is not the concern; rather it's the quality of the building materials, including insulation quality and tightness, and how these items impact the amount of energy necessary to satisfy heating and cooling demands - i.e. impact on the ability to maintain internal room temperatures in the context of heat loss in winter and heat gain in warmer months. 

7000sqft Norwell Home with Natatorium (Pool)
This more important consideration, building material quality, directly impacts the required size of the geothermal system and therefore the initial and recurring operating costs.  To minimize these costs, the owner should first invest in minimizing heat loss and heat gain.  It can easily be shown how the investment in building materials offers the greater value.
1750sqft Cape Ranch

If it's not clear why, a quick "how it works" overview might be helpful.  With water-based geothermal exchange systems, water provides or transports energy.  More specifically the system operates in one of two modes; either a supply (in case of heating) or removal of energy (in case of cooling).  The provision or extraction of energy will increase or decrease the temperature of surrounding matter.  The higher or lower the temperature of material, the more, or less, energy it contains. 

Community Geothermal - 10 Buildings on Single Closed Loop

In the case of geothermal energy, we are interested in leveraging or accessing the temperature of the earth’s crust – which has in fact captured and stored the sun’s energy. The rotisserie effect of the earth as it orbits the sun has given the earth’s crust a relatively stable and consistent temperature of 50-55 degF in the Northeast.
When we talk about ground source heat pumps (or geothermal heat pumps) we’re typically referring to a technology that utilizes water to conduct heat or energy from the ground into a heat pump which extracts energy and transfers it to the building through the use and conductive properties of water. 
In conclusion, because the geothermal system depends on water to transport the energy, the more energy required – the greater the water flow needed. The more water, the larger the loop field in the case of a “closed loop” system, or the greater the pump size and well water source needed in the case of an “open loop” system. 
Whether a closed or open loop system, the more water needed the more costly the system and the greater the disparity in initial cost between a traditional heating and cooling system versus a geothermal heating and cooling system.  Therefore it’s not the building size … but rather the building material quality that drive suitability of geothermal technology.

Sunday, March 17, 2013


We've been asked a number of times whether geothermal heating and cooling can work with an existing home.  The answer is YES ... however ... the context of the discussion needs to be adjusted slightly.

 Geothermal drilling of closed loop wells - each tied into the home to supply water to the geo-heat pumps.

Regardless of what technology you are considering for a replacement to an older less efficient heating system, the most important first step is giving attention to the quality of your home's building materials; more specifically INSULATION - which defines the ability of your home to prevent heat loss in the winter and prevent heat gain in the summer. 

Insulation is by far the least expensive way to improve the efficiency of your home.  Once you’ve improved your insulation in the attic, walls, basement, and basement sill, you’ve now significantly reduced the “size” and cost of the mechanical system necessary to heat and cool your home.

The reason this is more significant for geothermal is simple – the size of the geothermal loop is decreased.  While federal tax credits will typically cover the cost of your geothermal loop, by improving the insulation of your home, the initial system costs and the operating costs will be greatly reduced.

And after all, with insulation being the least expensive way to save money – it seems like an easy first step while you make your decision about which heating and cooling system is best. 

Our recommendation is to approach MassSave for an energy audit and do what you can to access the incentives and 0% heat loans available for upgrading.

Sunday, February 24, 2013

Net Zero Energy: Technical and Financial Feasibility

Net Zero Energy:  Technical and Economic Feasibility
We’ve been asked a number of times whether Net Zero status is achievable technically using renewable energy products and whether it makes economic sense.  
While there is considerable value to lower carbon emissions for our global environment, our commercial and, to a great extent, residential market choices remain driven by finite resources – i.e. money. Invariably, economics, including initial and recurring costs, ROI, and related payback are primary concerns when making decisions on whether to adopt renewable energy systems are appropriate.
One thing is clear – oil and gas are limited resources and will continue trending upward, and the question of whether renewable-based heating and cooling systems are economically feasible should be asked in conjunction with whether operating costs of traditional fuel-based heating and cooling systems are and will remain economically sustainable …
Our position is that typically no single renewable energy solution will enable Net Zero status in a way that makes sense financially.  Rather, if we approach energy efficiency using renewable more holistically by combining technologies, the Net Zero status or Holy Grail is not only achievable but affordable.
For example combining a highly efficient, well designed, Ground Source Heat Pump (GSHP) system with Solar PV and Solar Thermal can be a very cost effective, predictable energy solution.   Solar PV can provide the electricity required to run the highly efficient GSHP which is used for both heating and cooling.   Solar Thermal can provide nearly 80% of hot water requirements – thereby offloading the heating system, making the size of the heater smaller, with lower energy consumption requirements.
Additionally, there are non-mechanical pieces to this Net Zero puzzle that are equally important.  In fact, looking at the heating and cooling technologies as a complete system is only the first step.  One still needs to integrate not only high-performing heating and cooling technologies but also high-performing building materials – from the perspective of heat loss and heat gain.
Therefore higher quality insulation and R-values in the attic, walls, and basement are important components to achieving Net Zero status.  Higher quality windows, doors, and entry ways, are important contributors to minimizing heat loss in the winter and heat gain in the summer.
By minimizing heat loss and gain, renewable energy systems can be sized smaller, leading to lower initial costs, and lower operating costs.  With smaller heating and cooling demand (or load) on the system, these systems can run more efficiently and outpace traditional combustion systems (oil and gas) on initial and long-term recurring costs.