What Is It and How Does It Work?

If you have an existing home, there are many steps that you can take in order to reduce your energy use and save money on utility bills without building a new home. Energy efficiency retrofits can include a wide range of measure to save energy, some simple and inexpensive, and others more complicated with longer payback periods. By thinking about a whole house approach to your retrofit, you can maximize your home's energy efficiency by ensuring that every measure you take works well with all of your home's systems. If you are conducting a renovation of your existing home, you should be aware of which components already contribute to energy savings, and which need to be improved. The decisions that you make in order to improve your home's energy-efficiency are all interrelated, even if they seem like very different and disconnected components. For example, sealing gaps and cracks in your home can prevent infiltration which decreases drafts and helps to reduce heating costs. However, if you do not concurrently assure that your furnace is properly vented, your well-intentioned air sealing can lead to other problems. A poorly vented furnace can lead to a build-up of harmful gases within your home, as well as decreased efficiency and greater maintenance costs.

What Are the Options?

If your current HVAC system is getting old, replacing it with an ENERGY STAR certified system can help you start saving money and energy. ENERGY STAR qualified heat pumps and air conditioners can use up to 20% less energy than standard new models. If your existing system requires frequent maintenance or if you have noticed your energy bills going up, you are probably ready for a new system that can start saving on maintenance and energy bills right away.

Inconsistent heating or cooling patterns from room to room may be a sign of leaky ducts or poor insulation. You may think of your ductwork and insulation as separate from your air conditioning or heating unit, but they all work together keep your home comfortable, so you should think of them as system. Also, a great way of controlling that system is with a programmable thermostat. You can save money by setting the thermostat at different settings depending on when you are home or asleep.

There are other factors that may signal a need for a new HVAC system, such as humidity and dust problems. Inadequate ventilation caused by leaky ducts or malfunctioning equipment, can lead to dry air in the winter or moist air in the summer. Leaky ducts and dirty filters can also spread excess dust particles throughout your home.

Insulation provides resistance to heat flow in your home – preventing warm air on the inside leaving to the cold outside air during the winter, and preventing hot outside air from entering your home during the summer. A well insulated home will have lower heating and cooling bills. Because heat always flows from a warmer space into a cooler space, warm air flows into your house in the summer and flows out of your house in the winter. Insulation provides resistance to this heat flow all year round. The thermal resistance that insulation provides is measured by its R-value – the higher the R-value, the more effective the insulation will be, if properly installed.

Air Sealing

The roof of your home is potentially the most important barrier against extreme heat and cold. If your roof is poorly insulated, you will lose too much heat in during the winter, wasting energy on heating and raising your utility bills. If you have a dark, heat absorbing roof, you will experience too much heat gain in the summer, straining your cooling system and, again, costing more on utilities. There are a few strategies that you should consider in order to prevent excess heat gain and heat loss through your roof.

A Cool Roof is a type of roofing material that reflects sunlight and is resistant to absorbing heat. Roofs that are dark in color tend to absorb heat and can become very hot in the summertime. This puts an added strain on your air conditioner and makes your energy bills go up. Most – though not all – Cool Roofs are light in color and do not absorb nearly as much heat. Roofs that are dark in color can absorb as much as 90% of solar energy and sometimes get as hot as 150 degrees F on sunny days. Cool Roofs can absorb less than 50% of solar energy, which decreases the temperature of the roof, the cooling requirement inside the house, and the money you need to spend on energy in order to cool your home.

A Green Roof is a type of composite roofing system that includes a waterproof membrane, drainage, growing medium, and plants. There are many different ways to create Green Roofs and in most cases they are custom-designed for specific building conditions. However, as the technology becomes more developed, some companies have also developed comprehensive, modular systems that can be implemented in many different applications. These modular products are made out of interlocking units that include each of the components of the Green Roof.

The roof assembly materials of your home play a critical role in protecting the inside of your home from the elements. An effective roof assembly will be made up of materials that keep moisture out and prevent unwanted heat gains and losses. The components of a comprehensive roof assembly include a roof deck, vapor retarder, insulation, and a roof covering. In some cases, a single material can play multiple roles. For example, monolithic membrane roofing materials can serve as vapor retarders and roof covering. Steep-slope roofs and low-slope roofs require different types of roof coverings. The materials that make up your roof can deflect the sun's rays, keep rain and humidity from penetrating the building envelope, and protect your home from extreme heat and cold.

The windows on your house can be great energy-savers, but they can also contribute to inefficiencies if they are old, leaky, or unshaded. Well designed window apertures can provide daylighting that helps limit the use of electrical lights, views to the outside, natural ventilation for fresh air and passive cooling, and beneficial heat gain during the winter.

High Performance windows have a series of upgrades over traditional single-pane or double-pane windows with clear glass that help conserve energy and save money. While you can expect to pay more for high performance windows, the cost difference between windows with clear glass versus windows with multiple panes, selective coatings, inert gas, and other technological upgrades, can be made up in a relatively short period of time through energy savings. Windows are tested for several factors, and you should consider their performance on these tests when selecting energy-efficient windows. The tests are conducted by the National Fenestration Rating Council (NFRC) and are then used by ENERGY STAR in order to determine which products meet energy-efficiency standards. These figures will show up on a window’s label.

The factors to consider when buying new windows include: U-factor, Solar Heat Gain Coefficient, Air Leakage, Visible Transmission, Low-Emittance Coatings, and  an Air gap with Inter Gas.

Storm windows are single-pane glass or plastic panels that can be installed on either the inside or outside of your existing windows. They do not offer a significant upgrade in the insulation of old windows, but they have been shown to decrease leaking and air movement around existing windows. Usually they are installed in cold climates as an extra measure to keep buildings warmer during the winter.

Storm windows are a low-cost alternative to replacing your existing windows with energy-efficient windows. The long-term savings will be lower than if you replaced your windows, but you will see a greater pay back due to the significantly lower cost of installation of storm windows. If you are on a tight budget or live in a rental unit but still want to increase your apartment’s energy efficiency, storm windows may be the answer.

As part of a comprehensive strategy to make your window systems as energy-efficient as possible, you can add window treatments and coverings to reduce unwanted heat gain in the summer and heat loss in the winter. Window coverings can be a small, but effective step in reducing energy use when paired with other effective strategies. If you are considering adding window coverings to your windows, you may also want to think about caulking and weatherstripping to prevent infiltration, adding storm windows, or installing high performance windows with multiple panes and selective coatings to prevent even greater heat gains and losses.

Where Do I Start?

The first step to take before undergoing an energy efficiency retrofit is to have an energy audit performed on your home. Because there are so many different ways to improve your home's energy-efficiency, it can be difficult to know where to start. The best way to figure that out is by doing a home Energy Audit to determine where your home leaks, what equipment needs maintenance, whether you should replace your HVAC system, whether you need better insulation, or how much money you can save by replacing incandescent light bulbs with compact fluorescent bulbs. You can get very reliable guidance and data-based answers to these questions and more with a professional home Energy Audit, but you can also get a good idea for where the trouble-areas are by doing an energy assessment of your own.

At a minimum, you can perform a do-it-yourself home energy assessment on your own. If you are doing a preliminary home energy assessment on your own, there are a few key things you should look for.  There are some causes of inefficiency that you will be able to assess and even fix on your own, such as finding a leak around the edge of a window frame that you repair by applying caulk to the frame. Some problems will be more difficult to assess and require professional installation, such as figuring out whether your wall insulation meets current standards or has settled – and re-insulating your walls.

While a DIY home energy assessment is a good idea to familiarize yourself with your home's energy-efficiency issues, the best way to get a detailed idea of where your home is costing you money is by having a professional home energy assessment done by a qualified Energy Auditor. A comprehensive home Energy Audit will consist of a room-by-room visual assessment, a Blower Door Test, and a Thermographic Scan. Some Energy Auditors will also do a PFT Air Infiltration Measurement, but it is not necessarily standard practice.