Amory Lovins of the Rocky Mountain Institute has long advocated the concept of "negawatts". For some reason many people have difficulty equating reduced energy consumption as having the same value to a utility as generating new energy... especially the people running the utilities. Think about it. If you reduce electricity in your home by religiously turning off lights that don't need to be on and reduce your energy consumption by 1,000 kWh this month, those 1,000 kWh can be sold to another consumer. Is that any different to the utility than building a generator to produce 100 kWh to sell to that other consumer? Actually, it is....
To build a generator capable of producing 1,000 kWh, a utility has to make a large investment. Depending on the type of system, a utility has to spend somewhere between $1,500 to $8,500 to build the power generator and transmission lines to deliver power to your home or business.
In comparison, if energy efficient lighting was installed in a retail store, energy consumption can often be reduced by 1 Watt/square foot (11 Watts/m2). For every 1,000 square feet (93 m2) of space refitted with efficient lighting, power consumption is reduced by 1 kW. The cost of refitting the inefficient lighting would be in the range of $1,000. That frees up 1 kW of power the utility can sell to someone else, and eliminates the need to build a power plant to supply an additional kW.
So what does this have to do with a GCHP system? A building cooled with a conventional chiller or roof mounted air conditioners uses about 30% to 40% more electricity to deliver a given amount of cooling to a building. Simply replacing the conventional system with a GCHP system would reduce cooling energy by about 1 kW for every 1,000 square feet (93 m2) of space.
If efficient lighting were installed in addition to a GCHP system, every 1,000 square feet (93 m2) of space could free up approximately 2 kW of power the utility wouldn't have to generate...at a capital cost of between $3,000 and $17,000. When the GCHP system designer starts integrating thermal energy storage with the GCHP system, along with better windows, etc. the numbers start becoming even better. And when a designer works in an integrated design process with the building owner and building design team on a new project, energy consumption can be reduced by 50%, 60%, even 70% compared to a similar size building designed using conventional approaches.
The integrated design approach has an added benefit to the owner: When building heating and cooling loads are reduced, the cost of building a GCHP system and GHX for the building is often reduced enough to offset the additional cost of lighting and other energy efficiency measures integrated into the building...the overall cost of building a more efficient building can actually be less than business as usual.
The new Certified GeoExchange Designer (CGD) course offered by the International Ground Source Heat Pump Association (IGSHPA) and the Association for Energy Engineers (AEE) discusses this approach to the design of GCHP systems in detail, and is being offered at the IGSHPA Conference in Las Vegas, Oct 7-10, 2013.
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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