How much does closing blinds save on energy?

I wanted to calculate how much money I can save this summer by simply closing my blinds on hot sunny days.

Cooling my home during summer costs around $450 - so how much can I save?

Last summer in Melbourne, I paid an energy bill of $450, primarily due to keeping my home cool with our splt system air conditioning.

Prior to last summer, I had already gone around the house and filled in the gaps around the door and window frames. So, I wanted to focus on the fact that, in some cases, windows can contribute up to 87% of heat gain in a house.

I began thinking, “How can I cut down this cost while still staying comfortable?” I realised that a large chunk of the heat gain in my house comes from the windows, which are single-glazed in wood frames. This led me to investigate how simple changes, like closing the blinds early in the morning, could make a significant difference.

Orientation

One of the first things anyone will need to do is understand the orientation of the windows in their home. Simply put, investing in blinds and fancy sun-proof glazing on a south-facing window won't be nearly as effective as first addressing other windows in the house.

The Problem: High Energy Bills and Heat Gain

Windows can be a major source of heat during the summer, contributing to uncomfortable indoor temperatures. If 87% of heat can enter your home through windows, then it can force your air conditioner to work harder and increase energy consumption costs.

My air conditioner uses 2 kWh of energy. On a typical summer day, I would run it for about six hours, consuming 12 kWh per day. At a flat rate of $0.30 per kWh, this means I was spending around $3.60 per day to cool my home.

A possible solution is closing the blinds early in the day

After researching solutions, I learned that closing blinds or curtains during the hottest parts of the day could reduce heat gain by as much as 57%.

In that report, they use honeycomb blinds, which I currently don't have. So, I'm going to take a modest estimate and say my in-frame vinyl blinds will reduce my need for cooling by 30%. My daily energy consumption for cooling in summer would drop from 12 kWh to 8.4 kWh.

At $0.30 per kWh, this would bring my daily cooling cost down from $3.60 to $2.52, resulting in a savings of $1.08 per day. Over a 90-day period, this simple adjustment could save me approximately $97.20.

I could consider taking more steps

Besides being vigilant with closing the blinds, I’ve been considering adding external shading solutions, such as awnings or reflective window films, to further reduce heat gain. Also, external shading is identified as the best solution for preventing heat gain.

And on the topic of more steps I could take, the CSIRO also points out for each 1°C of temperature lower on my AC, my energy consumption increases by 5 to 10%. So setting the AC to 22°C instead of 18°C can be a huge cost saver! Combined with closing the blinds we can be saving serious money over summer!

Finally, my home is an old weatherboard that is nearing 100 years old, so it's a leaky boat of air. If I want to keep chipping away at these energy bills, I need to do a larger overhaul in draught proofing around the house as well.

$100 of savings for closing the blinds on hot sunny days

By adopting the simple practice of closing blinds during peak sunlight hours, I could have potentially saved over $100 just over summer. While this might seem like a modest amount, every bit helps, and the cumulative effect of making these adjustments across the entire home can make a noticeable difference. For a low-cost solution, this is a great way to cut down on energy use while keeping your home more comfortable.

If you’re dealing with high cooling bills like I was, I highly recommend trying this approach. Combined with other energy-saving methods, like external shading, and not blasting the AC in overdrive, you could reduce your summer energy costs significantly.

Energy saving tips relative to your consumption patterns

Through SolvingZero, we can connect to any smart meter in the country. By monitoring how your home uses its energy and asking a few questions, we can suggest simple and effective ways to help you lower your energy consumption in the moment. The suggestions could be simple text like, "It will be 32 today, don't forget to close the blinds before 10 a.m. to keep the cool air in." These small tweaks will add up day to day and week to week to become significant changes on your energy bills and emissions.