To help you save money by saving energy, we launched #AskEnergySaver — an online series that gives you access to some of the Energy Department’s home energy efficiency experts. During 2014, experts from the Department and our National Labs will be answering your energy-saving questions and sharing their advice on ways to improve your home’s comfort.

Summer brings warmer weather, backyard BBQs and trips to the beach. But with it also comes higher electricity bills as we try to keep cool and comfortable in the sultry heat. That’s why this month, we asked you to share your questions about saving energy during summer.

To answer them, we reached out to Sarah Widder, a research engineer at the Energy Department’s Pacific Northwest National Lab who focuses on improving the energy efficiency of our nation’s buildings. Widder also contributes to research at the PNNL’s Lab Homes — a project designed to evaluate how new building technologies work and calculate their energy savings for the typical American family.

What is the single biggest thing a typical homeowner can do to lower their energy bills without sacrificing too much comfort?  
— from Ken via email

Sarah Widder: The single biggest thing a typical homeowner can do to lower energy bills depends on the characteristics of the home and the occupants, the home’s climate and the homeowner’s budget. Where you live and how you live will impact what consumes the most energy in your home and where the biggest opportunities for savings are.

However in most homes, your heating, ventilation and/or air-conditioning equipment (HVAC) are likely to consume the most energy — accounting for 48 percent of the average home’s energy use — and homeowners should focus on measures that reduce the home’s heating and cooling loads to get the most bang for your buck in terms of energy investments.

The lowest cost way to reduce heating and cooling costs is to install a programmable thermostat and set it to adjust the thermostat setting higher in the summer and lower in the winter when the home is unoccupied. If you are willing to make a modest investment in your home’s energy performance, air sealing and insulating your home and ducts (if outside the conditioned space) can reduce space heating loads by up to 10 percent on average. In addition to saving energy, air sealing and insulating your home can make your home more comfortable by reducing drafts and allowing for more consistent room-to-room temperature distributions.

For more energy-saving tips, check out the updated Energy Saver Guide.

When leaving the house on vacation, should we turn down the thermostat and how low? Is there some (shorter) length of time out of the house for which it is not worth turning down the thermostat?
— from Forbes via email

SW: There are a lot of misconceptions regarding how thermostats work and, thus, how to properly employ them to save energy in your house.

So let’s start with the basics: what is a programmable thermostat? A programmable thermostat is a control switch that turns your HVAC system on or off to reach a desired interior temperature. In most cases, the thermostat does not affect the volume of air (or in some cases, water) being used to heat or cool your house, or the temperature of the air.

Adjusting the thermostat when you leave on vacation — or anytime you are not at home — will save energy for all heating and cooling systems, regardless of the length of time you will be away. A programmable thermostat is designed to save energy by decreasing the temperature differential between the outside and the inside. When the thermostat is set back, your HVAC system will turn off while your house “coasts” to the set back temperature and then will maintain that lower temperature (or higher temperature in the summer).

Setting back your thermostat set point decreases the amount of energy your house uses because it decreases the rate of heat loss or gain. That means the closer your setback temperature is to the outdoor temperature, the more energy you will save. Although, it is important to keep in mind that the farther you allow your house to drift from your desired house temperature, the longer it will take for your house to recover from the set back and return to a comfortable temperature.

When setting back your thermostat on a daily basis, a setback of 7-10 degrees F for eight hours a day can save as much as 10 percent on annual heating and cooling energy use. When leaving on vacation — usually more than three days — set your thermostat to 50-55 degrees F in the winter to prevent against freezing pipes and to 85-90 degrees F (or even turn it off) in the summer. If you live in a hot climate, it is best not to set your thermostat higher than 85 to 90 degrees F to protect any temperature sensitive building components or appliances, like your refrigerator.

There are a few exceptions to the above guidance. First, do not use a daily thermostat setback with a heat pump in heating mode, unless your thermostat is specially designed for use with heat pumps. Also in the summer, employing daily setbacks can increase peak loads for utilities and related carbon emissions — leading to higher energy costs and a larger environmental impact. In the summer on a daily basis, it is most beneficial to just set the thermostat back a few degrees or set it at a constant temperature as high as you are comfortable with.

For more ways to save energy at home check out Energy Saver.