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If you need to replace your heating/AC system anyway or are ready to make a big investment, consider switching to a renewable source of heating and cooling. These changes will cost more than a standard furnace or boiler upfront, but will save you each year on energy costs, especially if prices rise substantially in the long-term. Installing alternative heating and cooling systems is a major project. Unless you are creating a district heating and cooling system with others in your community, you will usually still keep some fossil-fuel heating and cooling source as a back-up, but will only use it in the most extreme conditions, saving significant energy. Some clean heating and cooling sources include:
Ground source heating, which exchanges heat from the ground with your building to warm it in the winter and dumps heat from your building into the ground to cool it in the summer (similar to how a refrigerator cools its inside by dumping heat to the outside). A ground source heat system uses some electricity to run, but saves substantially on winter heating and summer cooling – some Minnesota buildings with ground source heating don’t need any other back-up. To install ground source heat, significant open areas with permeable ground are needed to have access to. It is possible to do in a front and/or backyard, but may not be feasible everywhere. District ground-source heat systems providing heating and cooling to many homes on a larger scale may be possible in the future.
Solar heating – a growing number of home heating products are becoming available that use solar energy, and which are often installed within walls. When applied they can dramatically reduce the need for natural gas heating. These projects are financially feasible if you have the optimal set up of sun exposure, building structure, and can cover the upfront investment. Solar home heating technologies are usually not adequate to cover a buildings full heating needs, especially since the coldest days also have longest nights.
Electrical heating from renewable electricity is an option, but since electric heating is significantly less efficient and more costly, it is not recommended.
Neighborhood cogeneration – in the future, neighborhood energy facilities using biogas from anaerobic composting of food and yard waste could be used to generate district heat and electricity. These facilities already exist in downtown Minneapolis and downtown St. Paul burning urban wood-waste with some natural gas back-up. While they are much more efficient than having a furnace in each home, they continue to contribute to local pollution concerns.
An effective source of cooling are neighborhood/ commercial chillers that use electricity at night during the summer to produce ice and then use the cold from melting ice to cool buildings during the day. While this solution does not precisely save energy, it does shift energy use from day time (when electricity is expensive and in highest demand) to during the night when it is cheap and overproduced (and hence wasted). These systems are usually used on large commercial or institutional buildings, but could be developed at a neighborhood scale.
Renewable and clean sources of heating are relatively scarce, so a community-wide focus on air sealing and insulation is a prerequisite if these clean heating sources are to be as effective a solution as they can for your community. If we can get efficient enough to save 60-70% of our heating fuel needs, there’s a chance that we can find affordable and renewable heating solutions to cover the rest before energy prices get prohibitively higher.