Top 10 Eco-Friendly Heating and Cooling Solutions

Green heating and cooling systems are not only better for the planet but also help you save on energy costs. These solutions use far less energy than traditional HVAC systems.

Key Insights

Santa Clara University, a hub of innovation in California's Silicon Valley, is also a leader in green technology. In April 2011, the campus installed 60 solar panels on its student center roof to heat and cool the building. This large-scale solar system powers both the center's hot water and air conditioning systems [source: LaMonica].

The system operates with remarkable efficiency. Solar collectors capture sunlight and concentrate it, heating the building's water to 200 degrees. University leaders anticipate that this system will cut the building's natural gas use by 70 percent annually and reduce carbon dioxide emissions by 34 tons each year [source: LaMonica].

The university has leased the system for a 10-year period, paying a fixed rate for the energy the solar panels generate. Additionally, the school benefited from over $86,000 in state rebates [source: Santa Clara University].

Santa Clara University is just one of many institutions adopting green heating and cooling technologies. Universities, businesses, and homeowners alike are embracing these systems, which are more eco-friendly than traditional methods as they help reduce greenhouse gas emissions. Furthermore, these efficient green systems can lead to significant savings on energy bills. The U.S. Department of Energy reports that heating and cooling represent 56 percent of a home's total energy consumption [source: U.S. Department of Energy].

Green heating and cooling systems are categorized into two types: passive and active. Passive systems harness nature’s inherent ability to regulate temperature without the need for mechanical devices like furnaces or air conditioners [source: Green Technology]. Examples of passive technology include building homes with reflective, light-colored roofs to reduce heat absorption and using windows designed to trap cool air and block heat [source: Build it Solar].

Active systems, on the other hand, use various mechanical heating and cooling methods powered by solar energy, geothermal power, or other green energy sources.

The rise in green energy adoption in recent years is starting to show results. For instance, Americans saved over $19 billion in 2008 by utilizing various green heating and cooling technologies [source: U.S. Department of Energy]. However, these eco-friendly systems can be costly, with some solar collectors priced between $30 and $80 per square foot for installation. Fortunately, government incentive programs are available to help homeowners and builders offset some of the costs [source: U.S. Department of Energy].

Flip to the next page to explore the 10 best green heating and cooling solutions for your home.

10: Geothermal

Geothermal homes utilize heat pumps to harness the stable temperature found in geothermal wells beneath the earth’s surface. ©iStockphoto.com/LdF

The Earth holds an inexhaustible energy source — geothermal power. Deep beneath the surface, there is abundant hot water and steam, with temperatures increasing as you go deeper. However, you don’t need to dig too far to tap into this energy. Just a few feet underground, the temperature remains steady year-round, typically ranging from 42 to 80 degrees Fahrenheit (5.56 to 26.67 Celsius), depending on location. A geo-exchange system can harness this consistent energy to heat and cool almost any building [source: Minnesota Geothermal Solutions].

Geothermal systems don’t directly tap into the Earth's internal heat. Instead, these homes use heat pumps that leverage the consistent temperature of geothermal wells below the surface. The heat pump works year-round, cooling the home in summer and warming it in winter. Inside the pump, a fluid (either water or refrigerant) absorbs heat from the Earth when it’s cold outside and brings it indoors to warm the air. In the summer, the process reverses, cooling the house [source: APH Geothermal].

9: Solar (Passive)

The sun

is the ultimate source of green energy. Solar power is both constant and renewable, with no danger of it running out in the near future. However, you don’t need large, unsightly solar arrays to take advantage of solar energy. Passive solar energy systems are simple, involve minimal moving parts, and require very little maintenance. These systems utilize the natural principles of heat transfer rather than relying on machines like furnaces or air conditioners [source: Passive Solar Resources].

Passive solar technology harnesses the building’s walls, windows, and floors to collect, store, and release the sun's energy. However, passive solar homes still rely on mechanical systems like forced-air heating or radiant floors to maintain comfort levels, keeping the space cool during summer and warm during winter [source: Arizona Solar Center].

One of the simplest passive solar design systems is called 'direct gain.' In this setup, sunlight enters through windows and is converted into thermal energy. The walls and floors then absorb and store this heat. As long as the room temperature is warm, the home retains this heat. When nighttime arrives and temperatures drop, the stored heat is gradually released into the living space. Builders can also embed plastic or metal water pipes within the walls. When sunlight heats the walls, the water inside the pipes warms up, and this heated water can be circulated throughout the house to provide warmth [source: Arizona Solar Center].

8: Solar (Active)

Some people are happy to install solar cells on their roofs. These solar cells are made with photovoltaic materials that transform sunlight directly into electricity. This electricity can then be used to power the heating, cooling, and lighting systems of a home. Solar cells have been in use for decades, powering everything from spacecraft to calculators. However, there is a drawback: today’s cells are not very efficient, converting only about 10 percent of sunlight into usable energy [source: Herberman].

Furthermore, photovoltaic systems can be costly to install. The price for a complete photovoltaic system with solar panels typically ranges between $27,000 and $36,000. It may take about 12 to 15 years before the energy savings offset the initial cost. Fortunately, tax credits and other incentives are available to ease the financial burden of installing an active solar energy system [source: Scherzer].

There are also more affordable active solar heating options available. These systems use liquids, like water, or air to capture the sun’s energy. The liquid or air absorbs the sunlight through a collector, which then transfers the heat directly into the home or a storage unit. The collected heat is subsequently distributed throughout the house [source: U.S. Department of Energy].

7: Biomass

Biomass is both an environmentally friendly and cost-effective alternative to fuel oil, propane, and natural gas.

There’s nothing quite like the warmth of a wood fire during a chilly evening. Wood is a type of biomass, a renewable energy source derived from living organisms such as trees and plants. Biomass energy is natural and sustainable, as the plants and organisms capture solar energy. Biomass heating systems harness this stored energy and convert it into heat [source: Biomass.net].

Biomass is a sustainable, lower-cost alternative to traditional fuels like fuel oil, propane, and natural gas. Modern biomass systems, such as woodchip systems, burn cleanly and produce fewer pollutants than conventional wood stoves. Biomass systems release less carbon dioxide compared to fossil fuels because burning biomass only releases the carbon that the plant would naturally emit as it decomposes [source: Biomass Center]. Many schools, businesses, and homes now use biomass technology.

How much can biomass energy save? In 2008, officials in Wisconsin revealed that the state's schools could save hundreds of thousands of dollars by switching from natural gas to biomass. They estimated that switching to wood biomass would reduce heating costs by 29 to 57 percent, resulting in annual savings of between $53,000 and $75,000 [source: Focus on Energy].

6: Hydronic Heating

Hydronic heating systems have been in use for many years. Remember those old radiators in your grandmother’s house? Today, hydronic heating is much more advanced, using hot water that circulates through tubes under floors, inside radiators, or along baseboards to heat the space [source: HydronicHeating.net].

In hydronic systems, boilers heat liquids through solar or geothermal energy. While most boilers heat water, some systems use other fluids, like antifreeze. The heated liquid flows through plastic pipes into a heat exchanger, like a radiator [source: HydronicHeating.net].

Heat in a hydronic system is transferred in three different ways: conduction, convection, and radiation. Conduction occurs when heat moves from one object to another, like a spoon in hot water. Radiation is energy transferred through electromagnetic waves, such as the warmth you feel from a heat lamp. Convection is demonstrated when boiling water rises while cooler water sinks [source: HydronicHeating.net].

5: Absorption

Absorption heating and cooling systems operate without electricity, instead relying on solar power, geothermal energy, or natural gas, with the latter being the most common fuel. Absorption heat pumps function similarly to other heat pumps but have two key distinctions. First, an absorption heat pump uses a natural gas burner instead of electricity. Second, it employs a water-ammonia solution rather than a refrigerant. In winter, the solution absorbs heat from the Earth, and the pump circulates the heated liquid into the house to warm the air. During the summer, the process reverses [source: U.S. Department of Energy].

4: Biodiesel

Biodiesel is no longer just for vehicles. A growing number of homeowners are now using this clean-burning, renewable fuel to heat their homes. While it was once overlooked in favor of cheaper heating oil, the rising costs of oil have made biodiesel an increasingly affordable alternative. These BioHeat blends, containing 5%, 10%, or 20% biofuel mixed with heating oil, can all be burned in standard oil furnaces [source: Cuda].

Biofuels emit fewer pollutants, like carbon dioxide, into the air, helping reduce greenhouse gases. Additionally, biofuels come from renewable 'energy crops' such as wheat, corn, soybeans, and sugarcane, making them a sustainable energy source. However, there isn't enough biofuel to meet the demand for oil burners. Only 19 distributors in the U.S. provide BioHeat blends for residential customers [source: Cuda].

3: Ice-powered Air Conditioners

Ice Energy has created an air conditioner that uses ice to cool refrigerant during the hottest part of the day, instead of relying on the compressor of the unit. Ice Energy

Ice is excellent for cooling drinks, but can it really cool a modern home or office? A company called Ice Energy has introduced a system that turns water into ice, which is then used to power an air-conditioning unit.

On hot days, buildings and homes typically increase their air conditioning usage, which consumes a great deal of energy. Ice-powered air conditioners create ice overnight and use it to cool the refrigerant in existing air conditioning units during the day, reducing electricity consumption in the process [source: Ice Energy].

Here's how the system works: At night, the unit freezes 450 gallons (1,703.81 liters) of water by circulating refrigerant through copper coils. As the coils cool, the surrounding water turns to ice, which is stored for later use. The following day, when temperatures rise, the traditional AC unit is put on standby. Instead of using the compressor, the ice cools the hot refrigerant, helping to maintain a comfortable indoor temperature while cutting energy usage by about 30 percent [source: Ice Energy].

2: Green Coal

Did you just mention green coal? While coal is often regarded as one of the most damaging substances to the environment, it actually contains between 25 to 90 percent carbon. When burned, coal releases harmful greenhouse gases like carbon dioxide, sulfur, and nitrogen oxides, all contributing to global warming [source: Captain].

Through a technique known as gasification, researchers have discovered how to use coal's carbon to extract oxygen from water, producing hydrogen gas that burns cleanly as fuel. This hydrogen can be used to power turbines, generating electricity. The emissions from this process are stored underground, while other pollutants are transformed into solid waste that can be burned off [source: Captain].

1: Wind Power

Wind power is often associated with generating electricity, but did you know that it can also be used to generate heat? And the best part is, you don't need a massive windmill in your yard to make it work. In 2006, students from Oregon State University demonstrated this possibility by creating a compact wind turbine-powered water heater. Unlike traditional water heaters that rely on electricity or flames, their wind turbine system is entirely sustainable. It can even be mounted on a rooftop or any other windy location. The only requirement is sufficient wind to turn the turbine [source: Oregon State University].

When there's enough wind, the turbine causes a series of magnets attached to a metal plate to spin. As these magnets rotate near a copper plate, their magnetic resistance generates heat. This heat warms up the copper, and water flows through a coil of copper tubing on the back of the plate. This innovative design not only provides hot water but could also pump the heated water throughout the house, offering a potential source of home heating as well [source: Oregon State University].