Most homes, apartments, and offices have small exhaust fans in the bathrooms and potentially the kitchens.  These small fans are designed to operate for a short time to remove odors or humidity from a room and exhaust to the outdoors.  When the fan operates, it pulls air from the room, creating negative air pressure.  Air from other parts of the building or from the outdoors will move into the room to replace the air that was removed.  Most of the time, this replacement air comes from the outdoors.  Even though the fan is small, a kitchen or bathroom exhaust fan can remove a lot of heated or cooled air from a home or office.  Unless the outdoor temperature is the same temperature as the indoor air, the replacement air from the outdoors must be heated or cooled.  This means that the exhaust fan contributes to energy use in two ways: to operate the fan itself and to heat or cool the replacement air.  It’s easy to forget and let the fan run longer than needed.  Some ideas to consider:

• If you own your house or office, consider hiring an electrician to install a timer or motion sensor that turns the fan off automatically. 
• If you live in an apartment or rental home, try setting an alarm on your cell phone to remind you to turn off the fan in a few minutes.
• If you are installing or replacing a fan, install the appropriate size for the room to optimize the effectiveness of the fan. 

The news and social media are filled with short articles summarizing scientific studies or technical information.  Many of these articles (including frequently this blog) try to summarize the key idea or ideas in a few sentences or paragraphs.  This can sometimes lead to confusing or unintentionally misleading conclusions.  Be a discerning reader and follow up so that you have the full story.  You may want to check more than one source to see if the information is disputed elsewhere.  Here’s an example.

A brief article a few months ago stated that a study shows it is more energy efficient to heat water in a teakettle rather than in a microwave.  However, I have many questions about this study, and the answers to these questions might change how I apply this simple conclusion.

• Was the teakettle electric or was it heated on a stove burner?
• Was the stove a gas or electric stove?  Each has a different energy efficiency and carbon footprint. 
• Was the same amount of water heated in each test, or was there extra water in the teakettle since many of us heat extra to make sure we have enough to fill our cup?

I found many sources that agreed with the conclusion that if used appropriately, an electric teakettle is more energy efficient than using a microwave or a teakettle on an electric stovetop.  These sources also explained how the tests were performed.  However, there are other factors (source of energy, whether the appliance turns off automatically, how you use the appliance) that can affect this conclusion, and some of them are discussed in the articles below.  Now that I have done some additional research, I understand the conclusion and also the factors that may affect the validity of that conclusion.   
 
I like this article.  It includes some topics the others don’t.
http://insideenergy.org/2016/02/23/boiling-water-ieq/

This article has a nice explanation of one set of conclusions plus some additional tips on saving energy when you heat water.
https://www.treehugger.com/ask-pablo-electric-kettle-stove-or-microwave-oven-4858652

Here is another article from the US Department of Energy.  It did not look at using a teakettle on a stovetop. 
https://www.energy.gov/energysaver/articles/electric-kettle-takes-down-microwave-final-round-energyfaceoff