2 Holiday Decorating Mistakes That Run Up Your Energy Bill

November 16, 2017

This type of air purifier can cut down on summer allergies

Holiday decorating can be a lot of fun.

But if you’re not careful, your decorations may actually be making your HVAC system work harder. And the harder your HVAC system works, the more energy it eats (i.e. higher energy bills).

So, to help you manage your energy bills this season, we’ll share 2 big decorating mistakes to avoid:

  1. Covering or putting heat sources near your thermostat
  2. Closing or blocking your air vents

Let’s go into more detail about each of these mistakes and how to avoid them...

Mistake #1: Covering or putting heat sources near your thermostat

unobstructed thermostat

Leave your thermostat unobstructed so it can properly record your home’s indoor temperature

Why it’s bad for your HVAC system

If your thermostat is covered up or near a heat source, it can’t correctly read the temperature of the room/house, which could make your HVAC system work longer than it really needs to.

You see, your thermostat is the brain of your HVAC system. Its #1 job is to sense changes in temperature and alert the HVAC system to turn on and off.

For example, let’s say it’s a particularly warm December day and you set your AC to 75°. Thirty minutes later, the temperature in your home is 75° but your thermostat thinks it’s 79° degrees (due to the heat from a nearby candle display) so your thermostat tells your AC to continue running—even though it shouldn’t.


Don’t cover up your thermostat or put heat-emitting objects near it. In fact, just to be on the safe side, place any heat sources (candles, lights, heaters, etc.) on the opposite side of the room from the thermostat.

Mistake #2: Closing or blocking your air vents

Some homeowners put decorations in front of their vents or close them so air doesn’t blow on their décor.

But doing that jeopardizes your HVAC’s efficiency...

Why it’s bad for your HVAC system

Your HVAC system has 2 types of air vents:

  1. Return vents that suck in unconditioned air from your home
  2. Supply vents that blow out conditioned air into your home

We’ll explain why closing or blocking both of these vents is bad...

When you close/block return vents...

...you “suffocate” your HVAC system and force it to work harder and longer, which increases energy bills but also increases the risk of expensive repairs. 

unobstructed return vent on ceiling

An unobstructed return vent on the ceiling

You see, your HVAC system is like you— it needs to “breathe” in a certain amount of air to work properly. 

how air circulates in ac system

Air comes into your HVAC system through the return vent, then is cooled and heated before it’s pushed into your home.

But when you close return vents (the vents that “suck in” air), you lower the amount of air your system can breathe in. And if your system can’t inhale enough air, it will run longer and longer to try and heat/cool your home, which will increase your energy usage.

Low airflow due to closed return vents can also cause dangerous (and expensive) problems like…

When you close/block supply vents...

...you increase the amount of conditioned air (that you paid for) that is lost to duct leaks.

unobstructed supply vent

An open supply vent

When you close supply vents, conditioned air is trapped in the ductwork and pressure will build. Over time, that pressure will force air through leaks in your ductwork. And this means your system has to work harder and longer because all that hot/cold air isn’t reaching your home.

closed supply vents problem leaky ductwork

Air escapes through leaks in the ductwork when supply vents are closed

Don’t think you have leaks in your ductwork? Think again. Most homes lose 20–30% of conditioned air to duct leaks already, so when you increase pressure in the ductwork by closing supply vents, that percentage increases even more.


Make sure you leave your return AND supply vents open and unobstructed by decorations or clutter.

Want more energy-saving HVAC tips?

Just give us a call. We’d be happy to answer any questions you have or help you schedule an appointment if you need AC maintenance or a repair this holiday season.

Similar Articles: