How motion sensors can reduce energy waste at home

What motion sensors do

Motion sensors are one of the simpler pieces of smart home technology to implement, but there’s more happening beneath the surface than you might realize. Before deciding where to place them in your home, you should first understand why. 

How motion sensors detect occupancy

Most motion sensors rely on passive infrared (PIR) technology. A PIR sensor doesn’t “see” a room the same way a camera does — it responds to body heat and motion rather than simple changes in light level. This is why they’re generally reliable at detecting when a person is walking into a room versus a shadow crossing a wall, for example. 

Types of motion sensors

• Passive infrared (PIR) sensors: PIR sensors are the most common and the most affordable option, covering most residential needs.
• Microwave sensors: These sensors send out pulses of energy and read what bounces back, so they can detect movement through thinner materials and across a wider area. However, they’re more prone to false triggers from things like moving curtains. 
• Dual-technology sensors: Dual-technology sensors combine PIR and microwave detection and only trigger when both agree something is moving, which cuts down on false alarms, especially in busier spots. 

Where motion sensors are typically installed

Home motion sensors are usually installed indoors and are most effective in spaces that people pass through — like hallways, entryways, closets and garages. Outdoors, they’re a natural fit for driveways, porches and patios. They’re frequently integrated with lights and cameras as part of a broader home security setup. Wherever they’re placed, the goal is the same: light, heat or cool a space only when someone is there to use it. 

When no one is using a room, there’s little benefit in leaving lights on or heating and cooling the space the same way as an occupied one. Motion sensors provide occupancy data that connected devices can use to respond more intelligently.

Where motion sensors reduce the most energy waste

Once a sensor identifies whether a room is occupied, that information can be used in a few different ways around the house. 

Lighting in low-traffic areas

Energy-efficient lighting solutions often include motion-sensor lights, which are the simplest form of occupancy detection. In a hallway, closet or garage, it’s easy to flip a switch on your way in and forget to switch it off on your way out. A motion sensor removes that step entirely. It’s a small change that can help reduce lighting costs over time across several low-traffic rooms. 

Heating and cooling unoccupied rooms

While motion-detected lighting is an easy way to reduce energy consumption, the bigger opportunity presented by motion sensors is using their occupancy data along with a smart thermostat, so your HVAC system isn’t working to heat or cool rooms nobody’s using. This is typically where real energy savings can be realized, with the added benefit of a reduced carbon footprint. 

Standby power in empty spaces

Motion sensors can also help you spot devices that are quietly running in rooms no one is in, sometimes called “energy vampires.” Standby power can account for up to 10% of the average home’s energy usage.1 If a sensor shows a home office or media room has been empty for hours while a TV, gaming console or monitor is still drawing power, that’s a good sign those devices belong on a smart power strip that can be shut off remotely.

How motion sensors work with smart thermostats and HVAC systems

This is where motion sensors become less about convenience and more about real energy savings. When a motion sensor is connected to systems in your home, it can change how your home operates. 

Sending occupancy data to your thermostat

When a motion sensor is paired with a smart thermostat, it feeds real-time occupancy information into the thermostat’s decision-making technology. Instead of running on a fixed schedule, this type of system can respond to what’s actually happening in the home at any given time. 

Automatically adjusting temperature

Using the data from the motion sensor, the thermostat can raise or lower the temperature automatically when a room — or the entire home — is unoccupied. ENERGY STAR estimates that certified smart thermostats save the average household approximately 8% on heating and cooling annually, mostly by reducing heating and cooling in spaces nobody is using.2 It’s similar to HVAC zoning, but with automated sensors instead of thermostats for each zone.

The Comfort IQ™ bundle from Reliant puts this type of occupancy-based automation to work. In-home sensors work with the Vivint Smart Thermostat and Smart Comfort to help adjust heating and cooling based on whether the home is occupied.

Overriding automation when needed

Don’t worry that you’ll be too warm or too cold if you connect your HVAC system to motion sensors. If a room has cooled down automatically but you’d like it warmer, you can always manually override the setting. Automation helps save energy by identifying your occupancy patterns, but it won’t take away your control. 

Installation and cost considerations

Once you’ve determined where you’d like to place your motion sensors, the next question is how much it will cost and how much work will go into installation. 

DIY vs. professional installation

Basic standalone motion sensor light switches and fixtures are generally inexpensive and simple enough to install yourself. App-connected sensors that are tied into a broader smart home system usually take more setup, since they need to be paired with a hub or a thermostat. In that case, professional technicians can handle the wiring, pairing and testing for you. 

Sensor placement

Where a sensor is placed matters more than you might think. Height, obstructions like furniture or plants, and whether a sensor faces a window can all affect its detection range and how likely it is to misfire. High-traffic areas generally call for a wider detection angle, while low-traffic spots like closets use a narrower one. 

Sensors paired with a smart home program

If you’d rather not research, install and connect smart home devices yourself, consider a solution that includes professional setup. The Comfort IQ bundle includes free professional installation, helping take the guesswork out of getting your connected devices up and running.

Common motion sensor mistakes

A good sensor won’t help save you money if it’s not set up correctly. Here are a few things to avoid when considering the best options for your home.

• Poor sensor placement: A sensor mounted too high, too low or aimed directly at a window can miss activity entirely, or trigger constantly from sunlight or passing cars. 
• Ignoring sensitivity and timeout settings: Most sensors come with a default timeout, or the time a system stays active after the last motion is detected. The timeout is often longer than it needs to be, which can limit potential savings.
• Not connecting sensors to other smart devices: A standalone sensor on a single light switch is helpful, but it doesn’t add up to much when it comes to savings. Connecting sensors to a larger system, like a smart thermostat and your home’s HVAC, will help maximize savings and energy efficiency. 

How motion sensors fit into a smarter energy-saving system

Motion sensors have the capability to do so much more than turn on a light when you walk into a room. Connected to the right systems, they can seamlessly help reduce energy waste in your home.  

If you’re looking to enjoy the comfort and convenience that comes with one connected experience, the Comfort IQ bundle from Reliant may be exactly what you’re looking for. It includes a Vivint motion sensor and professional installation as part of a home setup designed to help you reduce your energy usage automatically. 

Sources

¹ Unplug These “Energy Vampires” to Avoid Energy Waste and Save on Utility Bills | CNET

² ENERGY STAR Smart Thermostats FAQs for EEPS | ENERGY STAR