As a homeowner, you may wonder what is energy efficient windows, and does it really help you save money? Well, as a matter of fact, it does help you save a good amount of money annually. Energy-efficient windows or some say it as energy savings windows are specially designed to prevent the heat or cold escaping from your home. Their increased insulation reduces the energy usage of your home. Some energy-efficient windows can also save money on lighting. Less efficient window coverings stay closed more often to keep the heat and cold out. This causes the inhabitants of the home to keep the lights on during the day time. With energy-efficient windows, you can use the natural outdoor light in the day time. This will help you spend less money on the powering and replacing the lights.
Here are a few things you need to know about energy-efficient windows:
1. Heat Conduction
A window conducts heat through the glass, frame, and insulation leakage. How much heat it gains or losses through the glass is a rated factor of energy performance. The U-factor is the rate at which the window conducts the heat flow. The U-factor number only refers to the glass and its glazing. The National Fenestration Rating Council issues the rating of the windows which measures the performance of any window. This includes the spare parts and the frame. Lower U-factor rating means more energy-efficient windows. The Solar heat gain coefficient or SHGC refers to the solar radiation that is allowed through the window. Higher SHGC rating means that the window will collect the heat during the cold months and spread it into the room. And lower SHGC rating means the window will keep the cooling cost low during the summer season. The air leakage rate measures the amount of airflow that occurs around the window. The lower leakage rating means the less outside air will come from the outside and also less air will escape from the house.
2. Sunlight Transmittance
Glazing on the window affects the sunlight transmission through the window into the house. Visible transmittance or VY and Light to solar gain or LSG are the ratings that measure the energy performance of sunlight transmittance. VT ratings range from 0 to 1. 0 means the window will transmit less sunlight and 1 means it will transmit more sunlight. The LSG measures the amount of sunlight it will transmit compared to the ability to block the heat. If the LSG number is high, it means the window will transmit more sunlight without adding any additional heat.
Energy-efficient windows come in many types and designs. Before choosing any style you need to determine what kind of energy performance rating suits you. If you live in a place where both hot and cold season comes then you should go with the low SGHC and U-factor rated windows. This will provide you the best energy savings. If you live in a place where only hot or cold weather, then you should go with the high SGHC and U-factor rated windows. After that, you should focus on the design on the window. Based on the design there are several types of energy-efficient windows. Here are some common types of windows.
- Awning: This type of window opens outward, it has a hinge at the top. When closed, the sash at the bottom presses against the window’s frame. This type of window allows less air leakage compared to the sliding windows.
- Casement: This type of window has its hinge at the side. the sash presses against the frame when it’s closed. This type of window allows less leakage of air than the Awning windows.
- Fixed: This type of window doesn’t open at all! It’s an excellent choice of energy efficiency but it’s not recommended where you need ventilation.
- Hopper: This type of window opens inward. The hinges are located at the bottom of the window. These windows also have a sash that presses against the frame. The air leakage rate is similar to Awning and Casement windows.
- Double and Single Hung: These windows slide vertically. These windows slide vertically. Double-hung sliding allows you to open the window from the bottom and the top. You can open single-hung windows only from the bottom. The leakage rate is generally higher on these windows than the hinged styles.
- Double and Single Sliding. Like the double and single hung windows, these windows slide. The difference is that these windows slide horizontally. With the double sliding window, both sides of the window open. You can open single sliding windows only from one side. As a sliding window, it is generally higher on the leakage rate scale.
Without proper installation, you cannot maximize the energy efficiency of your windows. Each window has specific manufacturer recommendations for proper installation. Following these instructions is important to ensure the windows are properly air sealed for maximum energy efficiency. This will involve caulking the frame and weather stripping certain components of the window.
Energy-efficient windows may not save you a lot of money if you want to see a quick result. But if you compare your annual spending on power with the less efficient windows then you will definitely notice the difference. he U.S. Department of Energy estimates that you’ll save between $126 to $465 a year by replacing single-pane windows in your home. And if you have double-pane windows then you’ll save up to $111 per year.