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July 31, 2012, by Josh Gentry

Designing Mechanical Systems in the New Natural Gas Age

Everyone by now has reaped the benefits of the new found abundance of harvest-able natural gas. I have seen one of our clients save over $100,000 last year alone from the lower gas prices. However, what does this mean for the future design of buildings?

First, I went to the Energy Information Administration and found the Annual Energy Outlook 2011 to see what the futures look like for energy cost per unit of energy. This data showed that the projected cost of natural gas for consumers will remain less then half the cost per unit of energy compared to electricity through 2035. That is longer then the projected life expectancy of the systems being put into these building. With the cost of natural gas being so low now and in the future maybe we need to start looking at new designs of our system to take advantage of this clean burning energy source. http://www.eia.gov/forecasts/archive/aeo11/

Currently the most efficient and common mechanical designs I see for new buildings are geothermal and variable refrigerant flow (VRF) systems which only utilize electricity to heat, cool, and ventilate the building. These systems are great when you look at only the building, but what about the production of that energy and the power needed to get it there. Most commercial buildings get there power from coal fired power plant miles and miles from the building. These plants are being regulated to be cleaner and more efficient every year, however it is still a very heavily polluting source of energy. Extra power has to be generated to overcome line losses from traveling across miles of wire to get to the building. That power then has to be transformed into the usable voltages the building requires which is not a perfect system. After you add up all of these power losses you will find your source power and the source carbon footprint of the building is a lot more then one might think.

This makes me think that maybe using electricity to heat a building is not the best route to go. When I look at a new building and I want to provide a great system that is energy efficient, low energy cost, and within budget for our client I don't know if geothermal or VRF is the best way to go anymore. With natural gas having the capability to be 99% efficient in heating, half the cost compared to electricity, little to no power loss getting it to the site, and a clean burning fuel I want to use it as much as possible.Radiant heating is one of the most efficient heating methods possible in delivering heat to a space. If I can pair a radiant heating system with a super efficient cooling system I think I can cut the carbon footprint, cost of energy, and maintenance for the life of that system significantly.

Another venue to use natural gas to reduce the carbon footprint of a building is through on-site power generation. On-site power generation is not a new concept, however the natural gas fuel cell is. In the past, on-site generation is only for large consumers of energy such as industry and campuses because it doesn't make fiscal sense with smaller consumers. However, the fuel cell is much more reasonable at lower output and has a footprint of a couple parking spaces. One thing you can do with onsite power that it can't do with a power generation plant is harness the heat from the generation. If the heat is utilized from the fuel cell you can increase the efficiency of your entire system to be much higher then any coal power plant and without the line loss.

I understand that solar photovoltaics, wave energy, and wind have zero carbon footprint and are a big part of our energy futures as well.  However, the systems we put in place today will not see electric being produced using these methods.