Canada and the northern states have a lot of ice rinks. Most communities across Canada with more than 500 people have a local ice arena that is the social center of the town...and they are typically the most energy intensive buildings in the community. And the sad thing is most of the energy they use is simply thrown to the wind through a cooling tower. And there's a lot of energy...the average ice arena operating 10 months of the year has to get rid of
Several times we've been asked to design a GCHP system when the client has already drilled a test borehole (in a couple of cases 2 test boreholes) and had someone conduct a thermal conductivity (TC) test. The test borehole and TC test were conducted before the size and footprint of the building had even been established and there was no idea of what the heating and cooling requirements of the proposed building would be. What a waste of money! Don't get me wrong...
About 2% of new commercial buildings in North America in the last few years have been built with a GCHP system, and few building managers have had the opportunity to operate a building with a GHX. What are these pipes coming in from the ground around the building? What do they do? What can I expect from them? How do I control the temperature of the heat transfer fluid coming from the ground?
Every so often I get a call from a drilling or mechanical contractor who has been asked to put together a budget price for a "so-called geothermal project". I say "so-called" because what they are looking at is not really a geothermal project but a conventional HVAC system with a token heat pump and GHX. I reviewed a project recently that...
Most people considering a GCHP system for their home or business have questions about the return on their investment. Will they save enough in energy cost to pay for the difference in cost between a conventional HVAC system and a GCHP system. If we, as designers and contractors can find ways of installing a system for less money and/or reduce energy costs more, we can improve the return on their investment. Hybrid options for a system can reduce the first cost...
Some people don't consider a GCHP system as "renewable energy". A GCHP system doesn't produce electrons that can be pushed through a wire. What it does do is reduce the need to push electrons down the wire in the first place...and it does it very well. It doesn't matter how the electricity you use is produced, if you use a GCHP system for heating or cooling, it will use less energy than virtually any other HVAC system.
I have to admit I am a little biased towards water to water heat pumps. You have so much more flexibility in designing a system with a water to water heat pump than with forced air heat pumps. One thing to consider: when you are producing chilled water with a water to water, you will get hot water. What you do with it makes a difference in how efficient the system is. When you use both the hot and chilled water produced by the heat pump, you effectively double the system efficiency.
Energy modeling, especially on a large, complex building, is a tedious and time-consuming process...but if you're designing a GCHP system and GHX, it's the most powerful tool in your toolbox. The building and building systems are something you can have some control over. There are a number of things you can do while the building is still in the early design stage by using an energy model, first to...
In over 30 years in this industry I've run into 2 clients that didn't make their decision to install a GCHP system based on economics. One client was a roofing contractors association that simply didn't want equipment mounted on the roof of their new building, and they determined that a GCHP system didn't need roof mounted heating and cooling units. For them the cost of the GHX was the price to pay for getting rid of roof mounted equipment. The other was...
In fact, the whole idea of this system is to keep the ground around it frozen. An air craft hangar in Anadyr, Russia, was built on permanently frozen ground. Typically, an expensive, insulated foundation would be built to prevent heat from the building to move into the ground it is built on from melting the permafrost. For this project, pipe was simply laid on the permafrost, covered with about 1' (300 mm) of sand and gravel and 6" (150 mm) of high-density extruded foam insulation. A conventional concrete slab was poured on top of the insulation with radiant floor heat pipe.
In my blog I'll be expressing my opinions about what I've the learned about ground coupled heat pump (GCHP) systems over the last 30 years. I've been very fortunate to work with many interesting people who are passionate about this technology...engineers, geologists, mechanical contractors, drillers, excavation contractors...in different parts of the world. I've learned a lot from them and will be using this forum to pass on some of the things I've learned and feel are important. Please feel free to use this information if you feel it's worthwhile...hopefully you can avoid some of the same mistakes I've learned from.
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