How to Maximize Your South-Facing Windows

Windows don’t just make your home look beautiful, maintain your privacy, or protect against the elements. They also play a major role in your home’s energy efficiency. High-performance windows can help you save on your monthly energy expenses and keep the interior temperature of your home at a comfortable level, no matter the season. 

However, some homeowners may be unaware of the benefits of south-facing windows. Energy-efficient, south-facing Direct windows can utilize solar energy in your home through passive solar design. If you are unfamiliar with this, read on. In today’s article, STL Windows Direct provides an overview of passive solar design and how it works. 

What Is Passive Solar Design?

Passive solar design, also referred to as climatic design, makes use of abundant solar power without the help of panels or other mechanical systems such as fans, pumps, and electrical controls. Instead, it utilizes the sun’s heat and releases it during periods when the sun is not up to maintain a comfortable indoor temperature, even when the power is out. As such, it’s the most cost-effective and easiest method to make your home energy-efficient. Not only that, but since you are using a natural energy source, the passive solar design reduces your carbon footprint.

Furthermore, passive solar design has two main elements: south-facing glass and thermal mass to absorb, store, and release heat. When designing a passive solar home, keep in mind that the south side of your house should have an obstructed view of the sun. If you are planning a window replacement project, be sure that there are no tall trees or multi-story buildings that can block your home’s access to the sun. It’s also important to avoid oversizing south-facing glass and make sure that it is properly shaded to avoid overheating and increased cooling loads in the spring and fall. 

What Are the Seasonal Window Considerations?

In a nutshell, passive solar homes work by collecting heat through south-facing windows and retaining it in materials that store heat, known as thermal mass. Since the sun rises in the east and sets in the west, the side of the home that is utilized for solar gain needs to be facing the south side. For this reason, windows that collect solar energy should face within 30 degrees of true south.

However, take note that passive solar home design has different considerations, depending on the season and climate. Below, we explain the role of passive solar design during winter and summer:

• Winter. In the winter, the sun appears lower in the sky than in the summer. During the day, the low winter sun can shine through windows and allow heat energy to be absorbed into the home’s thermal mass. Although south-facing windows allow heat into the home, their thin and transparent nature can allow heat to escape. To keep this from happening during winter and cool climates, window installation experts recommend that the glass panes are doubled or tripled. Additionally, an insulated window covering or thick shade can be used to help insulate the windows and maintain the heat in the home after the sun sets.
• Summer. In the summer, meanwhile, a passive solar home uses its thermal mass to keep the building cool. Thus, the summer sun is kept from reaching the thermal mass of the building to avoid overheating. A system of shading or an overhang is used to cover the window. This way, the sun’s heat energy is blocked to keep the indoor temperature cooler than the outside.

How Can Low-E Windows Enhance Passive Solar Design?

To maximize your south-facing windows, you should consider investing in Low-E windows with double- or triple-pane panes. Low-E or Low-Emissivity is the amount of radiation emitted or absorbed from a surface. It has a very thin coating applied to one side of the glass, which serves as an invisible insulation barrier for your windows. By installing Low-E windows for your window replacement project, you minimize the amount of infrared and ultraviolet (UV) light that enters your home without compromising the amount of sunlight. 

Thanks to their special insulating properties, Low-E south-facing windows can significantly reduce heat costs and keep your home at a comfortable temperature. While Low-E windows are extremely beneficial during the winter months, they also have their advantages during the summer season. Low-E windows located at the north end of your home can reduce heat gain in summer while still letting plenty of natural light inside. 

There are two types of Low-E windows: hard-coat and soft-coat. We list the following pros and cons of each type:

• With hard-coat Low-E windows, a thin layer of silver is sprayed onto the surface of the glass at a very high temperature. Since Low-E glass is not sealed into an insulated glass unit, its durability offers the possibility for added accessories such as blinds in between the panes. Unlike soft-coat, hard-coat Low-E is a more inexpensive option as there are fewer layers needed to be applied. If you live in a climate with cold temperatures all year-round, hard-coat Low-E glass is best for your window installation as it yields a higher solar heat gain coefficient.
• With soft-coat Low-E windows, meanwhile, two to three fine layers of silver are added to the glass. Although the addition of these multiple layers creates a fairly delicate glass, the better the glass performs at blocking UV rays and reducing solar heat gain. In fact, soft-coat Low-E windows can provide up to 70 less UV transmission compared to standard clear glazing. If you live in a climate that switches between hot and cold seasons, it’s best to get windows with soft-coat Low-E glass.

To reap the benefits of passive solar home design, get in touch with our ever-reliable team at STL Windows Direct. We understand the importance of energy efficiency. Our exclusive window line, Smart 365 Innovations, is designated as one of ENERGY STAR®’s Most Efficient Certified Products. Rest assured that our Direct windows will not only boost the curb appeal of your home but also help you save on energy expenses. Call us today at (314) 690-5800, or fill out our online contact form to request an estimate and get started with your window replacement project.