MECHANICAL SYSTEMS
Whenever you tighten up your home, install new ventilation equipment or combustion appliances, or make any modifications to your home that may affect the way air flows throughout your home, combustion safety is a priority. All combustion appliances need a certain amount of air to operate properly; this is called combustion air. Exhaust appliances also need an air supply to draw air and toxic gasses out of the house; this is called make-up air. Insufficient combustion and make-up air results in backdrafting and the build up of toxic gasses including carbon monoxide. Older homes depended on leaks in the home's construction to provide this air. As we create tighter, more efficient homes, the air supply must be found elsewhere. To avoid combustion and make up air deficits, select sealed combustion appliances rather than atmospherically vented appliances. Code also requires the installation of carbon monoxide detectors near bedrooms in new construction, and is recommended for all homes. To learn more about combustion safety and determine if your home has adequate air supplies, perform simple draft hood testing using the Combustion & Make-Up Air document from the Minnesota Dept. of Commerce Energy Information Center. Consult a professional HVAC contractor to answer questions you may have or if you think you have insufficient combustion appliance ventilation.
Utility Rebates
Costs of upgrading your mechanical and utility systems can be offset by rebates available through government organizations, utility companies, and even product manufacturers. The Database of State Incentives for Renewables & Efficiency (DSIRE) allows you to view available rebates & incentives from a variety of sources. The site links you to corresponding sites to guide you through the rebate process. The Minnesota Office of Energy Security also lists funding opportunities for home improvement projects and energy efficiency upgrades. Contact your utility company to learn more about what rebate programs or tax credits might be available for your area.
Heating Systems
Our cold Minnesota climate means we use a lot of energy to heat our homes. After you've taken steps to improve the air tightness and insulation of your home, consider a more efficient heating system to lower your heating costs. Learn more about heating energy sources & statistics by visiting the Energy Efficiency & Renewable Energy website on heating energy consumption in Minnesota.
Upgrading and Maintaining your heating system
After you've improved your home's efficiency through other energy conservation strategies, your new furnace or boiler can often be sized smaller than your current model to meet your heating needs. Invest in the most efficient model you can afford. Over the average 20 year life of a furnace, higher purchase costs are recouped through energy cost savings. As fuel costs rise, the payback on the additional initial cost are achieved even more quickly. Replacing furnace filters and performing routine maintenance also increases its efficiency and prolongs the life of your furnace while improving your indoor air quality.
Like every product you put in your home, you want to ensure that the system is being installed by a qualified professional. Look for professional HVAC contractors that have an accredited degree or have been certified by the Building Performance Institute, the National Comfort Institute, or another independently certified training organization. These professionals will know how to properly calculate system sizes and follow combustion safety protocol. Ask them to show you their calculations, and be sure they take the actual air tightness and size of your home into account. An oversized unit will have a higher first-cost and be less efficient, an undersized unit will struggle to keep your home comfortably warm.
Resources for:
Solar Thermal Air
Solar air heaters are typically the most cost-effective solar technology with the shortest pay-back. They use air as the medium to transfer heat from solar radiation to the air in your home. They work best on a vertical surface and can be integrated into walls and used as either individual room heaters or to supplement a whole-house heating system. Collector plates absorb solar radiation and heat the air inside the collector. Active solar collectors use standard HVAC motors and fans to push the heated air into a room or duct system. As the warm air leaves the collector, cool air is drawn in and heated. Warm air entering ducts can be directed to a heat recovery system; the pre-heated air from the solar collector lessens the burden on traditional heating systems.
COOLING SYSTEM
With some of the hottest summers on record occurring the past 10 years, we can expect a greater need for cooling systems in the future.
Types of cooling:
- Natural Ventilation
- Central Air Conditioners
- Ductless Mini-Split
- Room Air Conditioners
- Other options
A properly sized cooling system will create a more comfortable indoor environment by effectively cooling, dehumidifying, and circulating air. Neither an oversized nor undersized model will be able to achieve desired humidity and comfortable temperature levels. Have a professional HVAC contractor properly size and locate your new system; this will ensure that you have proper air supply and duct size, and have located the unit for optimal performance and sound control. Learn the details of installing and locating air conditioners.
Water Heating
Upgrading traditional domestic hot water systems (DHW) present a significant opportunity to save money on energy use and lessen your environmental impact. In most homes, gas or electric powered conventional hot water systems inefficiently heat a large supply of water and hold it for use. Replacing these old systems (which typically last 10 to 12 years) - even before they've reached the end of their lifespan - is often a worth-while investment. If you notice any leaking or have created an orphaned hot water heater with the recent upgrade of your furnace, it's time to think about replacement. Energy efficient replacement options include demand/flash tankless systems, indirect/ side-arm systems, heat pump water heaters, and solar hot water.
Another efficient option which often qualifies for utility rebates is a Drain Water Heat Recovery system. These recapture the heat in water going down the drain to preheat water entering a water heater, and are generally less than $400. Learn more
Ways to reduce your energy use in water heating:
- lowering your water heater temperature
- using cold water for laundry and running the garbage disposal
- insulating hot water pipes
- installing low-flow water efficient fixtures-Water Sense and ENERGY STAR
Before you buy a DHW, do your research. The Home Energy Guide document, Water Heaters, is a thorough guide to selecting and understanding DHW. As a recommendation, consider the following:
- What is the annual operating cost? Compare the yellow EnergyGuide tags to determine which model will save you money in the long run. More efficient models tend to have higher initial cost but save more than the added expense in energy costs savings over time.
- What is the First Hour Rating (FHR) of each model? This establishes how much hot water the system can supply in the first hour. This value is displayed on the EnergyGuide label and is vital to determining the right size for your home.
- Which size system do you need? Over and undersized models are inconvenient or expensive to operate. Consider your hot water usage, both peak and total use, to determine which size fits your needs.
- Is it an ENERGY STAR model? Not all DHW system types are labeled for ENERGY STAR certification, but if you select one that is, go for the certification. Depending on the type of system you choose, certified models can save you 30 to 50% on your water heating costs.
- Which fuel option is best for your home? If both hook ups are available, select gas. Because it is more efficient to use gas to heat hot water than electric, if you do not have a gas hook-up, explore in the cost of installing one if it is a possibility. If not, consider an ENERGY STAR rated electric heat pump water heaters. Learn more
Types of water heaters:
- Conventional water heaters- storage tanks
- Indirect/ Side-arm water heaters
- Demand/Flash tankless hot water heaters
Additional resources:
ACEEE - Water Heating
MN Office of Energy Security - Water Heating
Energy Savers - Water Heating
The Minnesot Sustainable Housing Initiative - Hot Water Heaters