The Energy Audit-Energy Costs

Most of the energy audits and assessments I conduct are because of a high bill complaint.  Some homes have heating related issue, some have specific equipment adding to costs, some, the homeowner just needs a little education.  When looking to decrease energy costs,  where are the best places save?  The Department of Energy has categorized and estimated the energy used by the typical American home…

Department of Energy

Surprise!  Heating in our climate has the largest share of the energy pie.  In Northern Minnesota, the heating season typically begins in September and lasts until May.  That gives us June, July, and August with little or no heating costs.  During the summer, many of us miss the cold so we operate air conditioners at least part of those months, the costs never completely go away.  Can we lower our heating (and cooling) related expenses? Absolutely!

What if we changed our heating fuel?  Heating with fuel oil or electricity typically cost more.  Can you change the fuel source to natural gas or propane?  How about changing an electric heat source to an off-peak system? I wrote a blog about heating fuels that you can read here.  As of late, I’ve become a big fan of air source heat pumps.  They’ve been around a while, but manufacturers have recently made improvements for cold weather heating.  Some models can efficiently heat a home to 20 degrees below zero.  I’ll be discussing both ground source and air source heat pumps in a future blog.

Air sealing and adding insulation can also reduce the heating and cooling expenses of a home.  I’ve said this several times, and I’m sure everyone is sick of hearing it, but I’m gonna say it again.  10% to 40% of your heating costs is due to air leakage.  Climbing into your attic and sealing every hole that has a wire or plumbing pipe in it will reduce the air leaks, and while you’re up there, might as well throw some additional insulation in.  R-49 is recommended for our climate, that’s 16 to 18 inches of fiberglass batts.  Oh, and those recessed can lights that have big holes poked through the ceiling, they should also be addressed.  Recessed cans will be getting a blog of their own in the future.  Of course, there’s lots more insulating and air sealing that can be done to improve the efficiency of a home, but that discussion will take several blogs to complete.  We’ll hit those later too.

My Kill-o-watt meter

The second largest part of the energy pie is cooking, lighting, and other appliances.  Unless you’re running a commercial kitchen out of your home, reducing cooking costs is tough.  People must eat, it’s part of life.  Just remember to turn off the cooking equipment when your done.  An oven that has been on for a couple days because you forgot to turn it off will raise your electric or gas bill.  The choice of your coffee maker can also have an impact.  The models that have timers and auto off features are cheaper to operate.  The models with the highest cost are the ones that keep the water hot all the time, ready for an instant cup or pot of coffee (basically mini water heaters).  A great tool I use to determine the energy use of plug-in appliances in my home is the Kill-A-Watt meter.  Leaving this meter plugged in for a period of time will record the energy used for the device.  Refrigerators, coffee makers, dehumidifiers, the Christmas yard decorations, any 120 volt plug-in appliance or device can be tested.

Lighting is also in the 33% portion of the energy pie.  Many of the energy audits and assessments I conduct for customers have updated their lighting to LED bulbs.  In my opinion, if a bulb burns out, it should be replaced with an LED.  Most incandescent bulbs will no longer be available after 2020, and compact florescent bulbs don’t compare in longevity.  I discussed watts, lumens, and Kelvin with regards to lighting in my last blog post, click here to read it.

The third biggest expense for your home is water heating.  If you have running water in your home, you’ve probably got a water heater.  The most common water heaters are either gas or electric, but I’ve seen fuel oil, wood, city steam, and solar hot water systems.  We are just going to talk about the most common gas and electric versions today.  Three main types of gas water heaters are the standard tank heater (lower efficiency), power vent  tank heaters (higher efficiency), and the instant on-demand or tankless water heater.  The standard tank uses an atmospheric flue to move burned exhaust through a chimney or vent by a draft.  In a new, tight home, this type of water heater can backdraft, causing carbon monoxide to enter the home. This type of water heater is in the 80% efficiency range.  The power vent gas water heater is more efficient and less likely to backdraft than the standard gas water heater.  The on-demand gas water heater is a great choice for many homes.  They take up less space, only heat the water when needed, and are very efficient.  The drawback is they require more maintenance.  On-demand water heaters heat the water very quickly, which can cause scaling inside the heater.  Periodic maintanance is needed to remove the scale.

105 Gallon Marathon water heater

There are a couple electric water heaters that I’m going to talk about in this blog.  The first if the standard tank electric, which does have an efficient cousin used in electrical off-peak water heating programs, and the heat pump water heater.  The standard electric water heater run in the 90% efficiency range but will typically cost more to heat the water than the equivalent gas model.  The typical family of 4 will have an electric water heating cost of around $40 per month in my area.  A great option in some areas is to participate in an electricity provider’s off-peak water heating program.  One of the programs available in my area can reduce the family of 4’s cost to an average of $15 per month.  Because the water is only heated at night, a large storage tank is required, such as the super insulated Marathon 105-gallon water heater.  Water temperatures inside the tank are suggested to be 130 degrees, about 10 degrees higher than normal, to supply a little more capacity of hot water for the home.  The last electric option is the air source heat pump water heater.  The heat pump heats the water by moving heat from air in the area it is located to the water.  This will reduce the air temperature in this area.  Not such a good idea to heat your home during the winter, only to have your water heater move the heat to your water.  I would only recommend this water heater in our climate if there is an area of wasted heat within the home, such as an oversized woodstove or some other heat source that radiates surplus heat.

The last section of the energy pie is refrigeration costs.  Refrigerators have become much more efficient over the last 30 years.  A fridge manufactured in the late 1980’s had an energy consumption of between 100 and 200 kilowatt hours per month.  In today’s dollars, a fridge that uses 150 kWh will cost nearly $20 per month to operate in my area.  In comparison, a new Energy Star rated fridge of the same type will use closer to 40 kWh and cost around $5.  Freezers have also benefited from the increased efficiency.  The trick with a freezer is to keep it full.  I see many freezers with only a few items that could easily be moved to other refrigerator/freezers in the home.  Turning off any unneeded fridge or freezer units will reduce costs.  One of the biggest refrigeration problems I see when conducting energy audits is a  homeowner who purchases a nice, new, efficient model and the old model is moved to the garage to keep a case of beer cold…AGH.  Another good future blog post-refrigeration.

Summer has finally arrived and many homeowners are starting their dehumidifiers.  How much can they add to your electric bill?  The topic for next weeks blog.

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