It's Earth Day today and if you want to make your home heating more efficient and ensure you're not wasting energy, you can take advantage of one of Amazon's deals on smart thermostats and heating systems.

Google is offering a similar discount on the Nest 3rd Gen and Nest E. It's just for today, however, and it's only offering 15% off its smart heating products. 

A smart heating system makes it much easier to see and track the heat you're using, which is the first step to using less and saving energy (and cash). Some smart heating systems use geolocation to automatically switch off the heating when you leave the house, so you'll never forget and heat it while it's empty. Others have open window detection, to stop you from accidentally heating your back garden.

Although we can't promise you'll recoup the money you spend in the very near future, a smart thermostat is a great way to take your energy expenditure in hand.

Here are the Amazon deals.

The Nest 3rd Gen

The Google Nest Learning Thermostat 3rd Gen is now available for £183, down from £219 on Amazon UK. Nest is one of the most reliable, best designed and easiest to use heating systems on the market.

The Nest 3rd Gen has a large, high res display (480 x 480) on a 53mm x 44mm screen. The new Farsight mode lets you set the display to show the target temperature or a clock that’ll be visible from across the room.

It now supports OpernTherm, which means that if you have a compatible boiler, Nest will help it to work out the exact amount of gas to burn to reach or maintain a set temperature. It’ll save energy and help to prolong the life of your heating system.

It also has hot water control, so you can give your hot water a boost and adjust the schedule from the thermostat or your phone. It works with Auto-away and will switch off the tank heater after two days.

Bear in mind that it'll probably need professional installation. To find out more about its benefits and features, read our full review.

Amazon doesn't have a deal on the Nest E but you can get it for £30 off via Google, where it's on sale for £169.15, down from £199. If you're not sure whether to go for the Nest 3rd Gen or the Nest E, we've got a guide to their pros and cons.

Google also has offers on accessories including smoke and CO2 alarms, indoor and outdoor cameras, speakers and bundles.

Honeywell Evohome

The Honeywell Evohome is currently available for £208.55, down from a RRP of £249.99 on Amazon UK. When we reviewed it, we rated it as the best smart heating system we’d tested.

If you buy, you’ll get a wireless room thermostat, with a large, full-colour touchscreen and built in Wi-Fi, and a wireless relay. You’ll be able to control the system via the screen or Honeywell’s app.

Evohome is a modular heating system and you can use the company’s system builder tool to find out which components you’ll need to create a bespoke home heating system for your house. It’s a great way to be able to set different temperatures in different rooms and it’ll work with underfloor heating as well.

Read our review to find out more.

Hive Active Heating 2

Right now, you can get the Hive Active Heating and Hot Water Thermostat for under £150. It has an RRP of £179 but it’s currently available for £148.99 on Amazon.

Hive is one of the best-looking smart thermostats around, with a glass, mirror-like surface when not in use. It’s a schedule-based heating system, although you can use it in conjunction with your phone’s GPS to switch off when you leave the house and turn back on when you come in again.

Hive has multizone support and the Hive ecosystem also features smart lights, sensors, plugs and security cameras. Have a look at our full review to find out more.

To see all of the smart thermostats we’d recommend, check out our round-up of the best smart home heating systems we’ve tested.