Efficient Renewable Energy Use At Home
Residential use of electricity consumes 30 percent of electricity supplied globally.[i] This makes house design for new buildings and the retrofitting of existing homes pivotal to living sustainably. The home design principles for living sustainably include reducing your energy needs at home, improving efficiency, and installing renewable energy and water heating systems to supply your needs.[ii],[iii]
House Design Principals for Minimizing Energy Use
For new buildings, in order to optimize the natural energy gained during the day, the house should be oriented to maximize the sun’s free heat for as much of the daylight hours as possible. Thus, in the Northern Hemisphere houses should be south facing, while in the Southern Hemisphere houses should be north facing. This orientation will also be optimal for solar photovoltaic and solar water heating systems.
Existing homes will pose challenges for ensuring natural energy gains are maximized while minimizing energy losses. A home energy audit can help you understand where your home is losing energy, what structural changes you can take to improve it, and what renewable energy systems you can install.
Consider the following energy-saving and efficiency principles, including home remodeling, before installing a renewable energy system.[iv],[v] You can apply the principles as best you can to your existing house design and budget, either by having professionals do it for you, or by doing it yourself.
Ensure your house has an airtight seal and utilizes maximum quantities of insulation in the walls, roof, and floor (but see the ventilation caution below). This will minimize heat losses during cold weather and keep the house naturally cool during the summer. Seal and weather-strip all cracks, joints, and large openings to the outside. Insulated cover boxes can be used for attics and non-utilized fireplace entrances.
An “airtight” seal should not compromise adequate house ventilation, to ensure healthy air quality. A heat recovery ventilation system will be required to eliminate the risk of poor air quality with an airtight house seal. Of course, if you don’t have the budget for a heat recovery ventilation system, then seal the house but permit some natural ventilation that can be mechanically controlled during extreme cold.
Further minimization of heat loss can be achieved by installing double-glazed windows, low-emissivity coating windows (which reflect heat back inside), or storm windows. Outside window shutters can also be installed, providing a cover over the window space to completely close it off in extremely cold weather. The use of a vestibule inside the main doorways (i.e., double doors) will minimize heat loss as well.
Two types of heat-exchange systems, ground-source[vi] and air-source,[vii] can be utilized to efficiently heat and cool your house. A ground-source or geothermal heat pump and exchange system is used to move heat energy below the frost line, or about two meters below the earth’s surface, where the ground temperature is ambient and constant all year round. During the winter and on cool nights the house is heated, and during the summer and in the daytime the house is cooled.
If your home remodeling budget is limited, you can consider making one room in the house or basement very warm and energy efficient for emergency use. This way you have a solution for keeping warm during a climate and/or energy crisis. Other emergency options are discussed below.
Renewable Energy Electricity and Water Heating
Once steps have been taken to minimize the house’s energy requirements, then consideration should be given to renewable energy system(s) that can be used to meet your electricity and heating needs.
Rooftop solar photovoltaic (PV) systems are the most common renewable energy systems used for providing home electricity. Solar PV systems are usually connected to the local electricity grid, thereby ensuring a reliable and continuous supply of electricity during sunlight and non-sunlight hours. Energy generated above your immediate needs is transferred back to the electricity grid, paying all or part of your monthly electricity bill. Install more electricity generating capacity than you think you will need, or ensure you can increase the system capacity in the future.
Solar PV with a battery storage system can be installed if your budget and space permits. Ensure your system can be upgraded to include a battery storage system, if it is not installed upfront. A battery storage system will allow you to be grid-independent 24/7, including during blackouts or in an energy crisis when electricity prices will rise.
Battery storage also allows you to take advantage of variable grid pricing tariffs, and use stored energy during peak electricity times when electricity prices are higher, such as in the evening and morning when electricity demand rises.
Don’t forget that there are other sources of renewable energy for your home, depending on where you live and your budget. If wind resources are available in your location, a small wind electric system[viii] or hybrid solar-wind electric system[ix] become options. If you have a river or large stream running through your land, then a microhydroelectric power system[x] becomes an option.
Hybrid systems will protect your electricity supply during variable weather and across different seasons. For example, during the summer there is more sun, which is ideal for solar PV, whereas during the winter there is generally more wind and rain (i.e., increased river flow) and less sunlight. Hybrid systems with a battery storage system better enable you to go off-grid without experiencing power outages. Likewise, in the event of a climate-forcing volcanic eruption that blocks out much of the sun’s light, wind and microhydroelectric power will give you electricity-generating options, as solar PV would be limited.
Alternative home sources of energy have been with us for centuries, so keep these in mind for emergencies. The Handbook of Homemade Power[xi] is a gem for learning more about do-it-yourself solar heated house designs, homemade electricity generation, solar water heaters, parabolic solar cookers and ovens (for outside use), homemade biogas production, and ramjet pumps for pumping water up small heights without electricity. This is the do-it-yourself book for those with a small budget and good practical skills.
If you have spare land, then plant plenty of trees for future firewood. You may never need or use that firewood, but others might need it at some point in the future.
Water heating can account for about one-quarter of your electricity usage, so it makes good sense to install a rooftop solar hot water heating system to supply this energy need. These systems include solar heat collectors with a well-insulated storage tank, and can be active or passive systems. The system you install will depend on, first, whether the temperature in your area falls below zero degrees Celsius; second, on your budget; and third on the available space.[xii] Other options exist, including air and ground heat pump water heaters.[xiii]
A hot water backup system is useful in conjunction with a solar hot water heating system for high demand times and for cloudy days. You can also lower the thermostat on your water tank, reducing your standby heat loss. Insulating your hot water tank and pipes will improve hot water heating efficiency. Insulating the hot water pipes also means heated water is available instantly, saving you from having to pour precious water down the drain.
Heat recovery from wastewater or effluent water can be achieved by using drain-water heat exchangers. These heat exchange systems can be used with showers, bathtubs, sinks, dishwashers, and clothes washers. This heat can be stored for later use.[xiv]
Energy Efficiency at Home
The majority of electricity in the home is used for heating and cooling, lighting, water heating, and running high-energy appliances like washers and dryers, dishwashers, refrigerators and freezers, and televisions.[xv],[xvi]
A house utilizing the latest energy-efficient electrical appliances and heating systems uses less energy than a house utilizing old, low-efficiency electrical items. However, a house equipped with energy-efficient technologies will fail to achieve its potential energy performance and savings if you ignore how and when to use electricity.
Paying close attention to temperature settings and timings used for space heating and hot water saves energy. Upgrading heating and cooling systems to more energy efficient systems will also save energy.
If you don’t live in a very cold region, do you need to use a home heating system when just putting on warmer clothes will keep you warm? Should windows or doors be open when the heat is on? Do you need to heat the entire house if only one or two people are at home?
Changing conventional light bulbs to low-energy, light-emitting diodes is an obvious energy-saving measure. Likewise, turning lights off in rooms not in use, or installing movement sensors to do it for you automatically, will save electricity.
Consider if the fridge needs to be so cold. Do you need a hot wash for the washing machine? Filling up the dishwasher and washing machine fully before putting it on saves electricity and water. Why not dry your clothes outside using sunlight and fresh air rather than an electric dryer? All these things can save energy and money.
[i] U.S. Energy Information Administration (EIA). Global energy by fuel type and delivered energy by sector (not including 25.5% of electricity and heat related losses during energy conversion). EIA, Annual Energy Outlook 2017, DOE/EIA-0383(2017) (Washington, DC: January 2017). Data used; https://www.eia.gov/outlooks/ieo/excel/appf_tables.xlsx.
[ii] New Zealand Government. Ministry of Business, Innovation, and Employment. Smart Guides. Hikina Whakatutuki. Practical Advice on Smarter Home Essentials. https://www.smarterhomes.org.nz/smart-guides/. https://www.smarterhomes.org.nz/smart-guides/siting-and-location/house-orientation/. https://www.smarterhomes.org.nz/smart-guides/design/. https://www.smarterhomes.org.nz/smart-guides/power-lighting-and-energy-saving/, https://www.smarterhomes.org.nz/smart-guides/heating-cooling-and-insulation/.
[iii] US Department of Energy. Office of Energy Efficiency and Renewable Energy. https://www.energy.gov/eere/efficiency/homes, https://www.energy.gov/energysaver/about-us
[iv] New Zealand Government. Ministry of Business, Innovation, and Employment. Smart Guides. Hikina Whakatutuki. Practical Advice on Smarter Home Essentials. https://www.smarterhomes.org.nz/smart-guides/. https://www.smarterhomes.org.nz/smart-guides/siting-and-location/house-orientation/. https://www.smarterhomes.org.nz/smart-guides/design/. https://www.smarterhomes.org.nz/smart-guides/power-lighting-and-energy-saving/, https://www.smarterhomes.org.nz/smart-guides/heating-cooling-and-insulation/.
[v] US Department of Energy. Office of Energy Efficiency and Renewable Energy. https://www.energy.gov/eere/efficiency/homes, https://www.energy.gov/energysaver/about-us.
[vi] US Department of Energy. Geothermal Heat Pumps. https://www.energy.gov/energysaver/heat-and-cool/heat-pump-systems/geothermal-heat-pumps.
[vii] US Department of Energy. Air-Source Heat Pumps. https://www.energy.gov/energysaver/heat-pump-systems/air-source-heat-pumps.
[viii] US Department of Energy. Small Wind Electric Systems. https://www.energy.gov/energysaver/buying-and-making-electricity/small-wind-electric-systems.
[ix] US Department of Energy. Hybrid Wind and Solar Electric Systems. https://www.energy.gov/energysaver/buying-and-making-electricity/hybrid-wind-and-solar-electric-systems.
[x] US Department of Energy. Microhydropower Systems. https://www.energy.gov/energysaver/buying-and-making-electricity/microhydropower-systems.
[xi] Mother Earth News Staff, Handbook of Homemade Power. Bantam; 11th edition (1980). ISBN-10: 0553143107. https://www.amazon.com/Mother-Earth-Handbook-Homemade-Power/dp/0553143107/.
[xii] US Department of Energy. Solar Water Heaters. https://www.energy.gov/energysaver/water-heating/solar-water-heaters.
[xiii] US Department of Energy. Heat Pump Water Heaters. https://www.energy.gov/energysaver/water-heating/heat-pump-water-heaters.
[xiv] US Department of Energy. Drain-Water Heat Recovery. https://www.energy.gov/energysaver/water-heating/drain-water-heat-recovery.
[xv] US Environmental Protection Agency. Energy and the Environment. Electricity Customers. Electricity Customers. https://www.epa.gov/energy/electricity-customers.
[xvi] U.S. Energy Information Administration (2018). Use of electricity in the USA. https://www.eia.gov/energyexplained/index.cfm?page=electricity_use.
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