Can Energy-Efficient Windows Save Me Money?

Unless our windows are literally falling out of their frames, we don’t usually talk about replacing them due to the high upfront costs. Plus, let’s face it: they don’t immediately enhance the curb appeal of our spaces. So when we were asked to write an article on energy-efficient windows, with all their purported benefits of keeping heat out, we had to ask, worth it meh? Can they really help us save on our utility bills in the long run? In the face of cheaper options like window films and black-out curtains/blinds, are energy-efficient windows the better alternative? Let’s find out:

What are energy-efficient windows anyway?

In Singapore's warm climate, energy-efficient windows are designed to minimise the amount of heat entering your home. This not only results in a cooler home but also reduces the energy your air conditioner needs to achieve a comfortable temperature.

Ultimately, this can translate into some savings on your utility bills because your AC doesn't need to work as hard. Energy-efficient windows achieve this heat reduction through insulation or a special coating that deflects heat away from the home.

Design: SG Interior KJ

Note that energy-efficient glass pane does not equal an energy-efficient window. There is a need to take the whole window system as a whole. A badly aligned window with gaps (e.g. light comes through the frames) can cause the entire window system to fail as an energy-efficient window.

How much do energy-efficient windows cost?

Design: Monoloft 

Swapping out a standard 3m wide by 2m high window for high-spec energy-efficient ones will set you back around S$7,000, according to Sean Liew, General Manager at Sapphire Windows, a Singapore-based provider of energy-efficient windows. This price includes the removal and disposal of old windows.

For comparison, going with blackout curtains would cost about S$1,400, which is approximately five times less expensive.

How much savings to your electricity bill?

Sean estimates that we could save an estimated S$1,568 per year assuming today’s SP tariff rate of S$0.31 (incl. GST). This calculation also assumes we are using the air conditioning for 12 hours a day in a home with 100 square metres of windows.

For HDBs with around 6 square metres of windows and an air-conditioning usage of around 8 hours a day, the estimated annual savings then are around S$42. This means that recouping the initial upfront costs of about S$7,000 would take approximately 166 years. In other words, it is unlikely that you will fully recover the cost of energy-efficient windows solely through energy savings. 

Energy-Efficient Windows vs. Window Treatments

So because of this high upfront cost and the fact that we are unlikely to recoup what we initially put out, most homeowners tend to turn to cheaper alternatives like window films and blackout blinds/curtains to keep out the heat.

Window films and blackout blinds/curtains offer some level of heat insulation, but in truth, they are not as effective as fully insulated windows. Window films adhere directly to glass panels, so they cannot reduce heat gain through the window frames. Similarly, blackout curtains leave small gaps around the edges, allowing some heat to still pass through.

Other benefits of energy-efficient windows

While energy-efficient windows can't really save us money in the long run, the fact is, they do give us a significantly cooler home. And for some, that's money well spent. Plus, if you limit your AC usage, it's better for the environment as a whole.

There are other benefits energy-efficient windows offer as well, the most notable being sound insulation. This means they can significantly reduce noise levels from outside.

Sapphire Windows' energy-efficient windows claim to reduce sound by about 45 dB, which is a substantial advantage if you live near a busy traffic intersection or close to an MRT line.

Image courtesy of Sapphire Windows 

The energy-efficient windows from Sapphire Windows are also designed with security in mind. Their multiple points locking system, featuring locking mechanisms on 3 sides of the window, makes it difficult for burglars to break the lock. They’ve had 5 clients who had burglars attempting to break in through their windows using crowbars, but none of the attempts were successful.

Who should invest in energy-efficient windows?

If you spend a significant portion of your day at home, such as working remotely, and switch on the AC for a substantial amount of time, you may want to consider investing in energy-efficient windows that will help your AC work more efficiently. You would benefit particularly if your windows receive direct sunlight during the late morning or afternoon hours, typically those facing east or in the northwest or southwest directions.

Design: Fineline Design

Even if your windows don't face those directions, Singapore's consistently warm climate can still make your home feel uncomfortable. It's worth considering energy-efficient windows if you feel the fans in your home aren't enough for cooling down your space.

What to look out for when buying energy-efficient windows

For those who decide to take the plunge, look at energy efficiency of the whole window as a system, rather than look at the efficiencies of each individual component. Don't just look at the glass or the frame separately. A very good insulated glass double-glazed unit paired with a normal aluminium frame will result in an overall poor performance of the window, as the heat from the exterior will be gained and passed into the home through the frame anyway. So in other words, all or nothing! 

Image courtesy of Sapphire Windows 

Look out for a low U-value (the lower the better) for both the frame and the glass, Sean recommends. In Europe, they are pushing below the U-value of 1. In Singapore's context, values around 1.4 to 1.6 are good enough. 

For frames, UPVC (unplasticised poly-vinyl chloride) frames or thermally broken aluminium frames (with an insulated barrier between) are able to do the job as plastic is essentially a non-conductor. Pair them with a double-glazed glass unit, preferably with low-E coating (to minimise UV and infrared light) and even argon gas (to improve insulation) in the spacer area.

For those living in HDBs, make sure you also read up on the strict regulations by HDB before deciding to change your windows.

Care for your windows properly!

Since replacing windows is expensive, maintain them properly to extend their lifespan. Sean recommends inspecting your windows every six months for signs of rust, corrosion, or loose parts. “Simply open and close your windows a few times, or slide them along the track if they have a sliding system,” he advises.

Design: E+e Design 

If everything appears to be in good condition, lubricate all moving parts with a suitable lubricant, such as a silicone-based one, to enhance their longevity. Remember, maintaining your windows is the homeowner's responsibility. If a window falls off due to negligence, the homeowner will be held accountable.

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Energy-efficient windows offer benefits like reduced energy bills and improved thermal insulation, but they come with a high upfront cost and long payback period. Consider your energy usage, budget and priorities to decide if they are right for you.