Modern architecture is very much focused on energy efficiency and ecology. Our homes should be comfortable as well as eco-friendly, especially since January 2017. New technical requirements for energy efficiency of buildings have changed the way we perceive certain aspects of our homes. On the other hand, current designs are all about large glass units. That makes choosing windows and doors even more difficult.
Making your windows and doors more energy efficient will reduce your energy bills and lower your carbon footprint. It will also make your home a better place to live. How to upgrade your windows and doors?
How do windows and doors make your home more energy efficient?
When thinking about energy efficiency, most of us have heating in mind. The aim is to maintain thermal comfort indoors and, at the same time, lower energy consumption. For this reason, we look for solutions that will help us improve our house insulation. But that is only a half of the issue. Energy efficiency refers to lighting as well. Artificial light uses energy. Being less dependent on it, we can lower our electricity bills. To decrease our dependence on artificial light, we choose bigger windows that let more natural light in. Modern energy efficient windows and doors are the answer.
What window parameters should you pay attention to?
While looking for energy efficient windows and doors, we come across many creative terms, such as best insulating windows, energy rated windows or energy saving windows. Meanwhile, the most effective way to choose good windows and doors is to check their technical parameters. There are five of them:
– the window’s heat transfer coefficient (Uw),
– the heat transfer coefficient of the glazing unit (Ug),
– the heat transfer coefficient in the window frame (Uf),
– the light transmittance coefficient (Lt),
– the acoustic insulation coefficient (Rw).
The first four are essential for the energy efficiency of your home. Why? While comparing and contrasting technical parameters of certain products, customers tend to forget that energy efficiency does not refer to the heat only. The amount of natural light flooding in through the glazing unit is also important. It helps us to reduce our electricity bills and, therefore, lower our carbon footprint. What’s more, natural light is well-known as beneficial for our health and mood.
The window’s heat transfer coefficient
The Uw informs you about the level of window thermal insulation. It shows how much heat will penetrate 1 m2 of a window in one hour, with a one-degree difference between the temperatures on both sides of the window. The Uw (U-value) is the first parameter to look at. The lower it is, the better the window’s thermal insulation is.
The Uw refers to the window as a whole (U-value for passive windows starts from 0.9 W/m2K, therefore it is more important than the Ug, which refers to the glazing unit only. It does not mean that the Ug parameter is irrelevant in the selection process. It is not, but can be safely considered as secondary to the Uw.
The heat transfer coefficient of the glazing unit
The Ug describes the heat transfer coefficient of the glazing unit. The higher it is, the more sun radiation reaches the interior of your home. The lower it is, the smaller the heat losses during the heating period. And here is the problem: Should we try to gain as much thermal energy from the sun radiation as possible or lower the heat losses in winter? Taking an extra advantage of sun radiation in winter could be beneficial, but the truth is, it is very inconvenient during summer months. For this reason, it is better to choose windows with lower Ug coefficient and limit the heat losses rather than maximise the sun radiation. Optimal Value of Ug is 0.5 W/m2K, for triple glazed units and 0.6 for double-glazed units.
The heat transfer coefficient in the window frame
The Uf describes the heat transfer coefficient in the window frame. It is influenced by the width of the applied window profiles as well as the materials used in their production. The most common material is steel. Steel improves the mechanical strength of the plastic and makes the windows more durable. Unfortunately, it “gives off” more heat. To provide better thermal insulation results, window manufacturers started using composite fillings. Composite offers good mechanical strength and very good thermal insulation results. The best, however, is wood. Wood frames keep heat perfectly.
As far as the Uf parameter is concerned, the minimum value you should pay attention to is 1.1 W /(m2K).
The light transmittance coefficient
As we have already mentioned, light transmittance has a positive influence on the energy efficiency of your house. The Lt is a parameter describing the light transmittance coefficient. It informs you how much sunlight enters the room through the glazing unit. The Lt value depends on the thickness of the glass, the composition of the raw materials in the glass mass and the coating system used. If you want to take the most advantage of the sunlight in your home, you should choose windows with high Lt parameter. The parameter is defined as a percentage.
Double-glazed or triple-glazed windows: Which are better for your home?
Are you wondering if the number of panes can affect the energy efficiency of your home? The answer is positive. The number of panes really matters and can make a huge difference. The choice should be based on the location of your home as well as the destination of certain rooms. Double-glazed windows let more heat from the sun in, thus the rooms heat up faster. In colder climates, you will benefit more from better insulation. Triple-glazed windows will lower the thermal losses, which is particularly relevant in the case of the windows that are not exposed to a great deal of sun during the winter months.
When is a double-glazed unit enough?
In moderate climate, double-glazed units are considered enough in rooms which are used less frequently, as well as in the areas which are not usually kept at a higher temperature. They can be safely installed in basements, garages. It is also possible to choose double-glazed windows for rooms located in the more sunny part of the house. Double-glazed windows are also enough for buildings with just a few windows or small windows.
Double-glazed Window schema
When to choose a triple-glazed unit?
Triple-glazed windows are beneficial in moderate and cool climates, especially in the rooms with large glass units. They help to keep the temperature on the desired level and, at the same time, let a lot of natural light in. Triple-glazed windows are highly recommended in living rooms and bedrooms.
High quality triple-glazed units meet requirements for passive windows easily, and thus can be installed in modern passive homes. A passive window is characterised by the heat transfer coefficient Uw that is equal or lower than 0.8 (W / (m²K).
Triple-glazed Window schema
Improve energy efficiency of your home with high quality windows and doors
The most effective way to improve the energy efficiency of your home is to choose high quality windows and doors. The choice will result in:
- lower consumption of heat energy,
- lower consumption of electricity,
- better living conditions (thermal comfort and natural light).
While choosing windows, pay close attention to technical parameters, especially the values of the Uw and Lt parameters. They are essential for lowering the dependence on heating and artificial light during the day, and thus, improving energy efficiency of your home.
You can achieve the best thermal insulation parameters by choosing triple-glazed windows equipped with a low-emission glazing unit with a warm edge spacer and inter-glazing space filled with a noble gas (such as argon). Do not forget about the frames. Energy efficiency depends on the material window frames are made from. The best results are offered by wooden frames, which keep heat in a perfect way. The whole construction should be complemented by a third gasket inside the frame which improves insulation as well.