The Energy Assessment

This is the first time I’ve been to this home.  The first time I’ve met the people living in this home. But I know a little about them.  I have two years of electricity use data to form a basic impression.  They use a lot of power. Even more in the winter.  You see, we live in a very cold climate, it costs something to keep warm during the long, cold winter.  This home uses more than most.

I’m conducting this energy assessment in late 2019.  An energy assessment is me giving my best guess at what I see during a home visit as to why the electricity or heating fuel costs aren’t meeting a homeowner’s expectations. There’s usually no or little testing of the home.  This assessment is free to the homeowner, a service provided by the electricity provider serving this home.

Entering the home, I’m met with a warm handshake and a common question, “where do we begin?”  I tell the people living in this home, a very large, almost McMansion style home built in 2010, that I will be asking several questions.  This is my way of getting to know as much as possible about how the home was built, what equipment is operating in and around the home, and how the homeowners live in their home.  What are their habits?  How many other people live in the home?  All the questions I ask will help me figure out why they use up to 10 times the electricity of a more efficient home.

As I sit with the homeowners asking questions, I find out some details.  They have 2 geothermal heating systems, one supplying forced air heat and air conditioning to the main two levels of the home, a second hydronic unit heating the basement floor and heated garage.  (A clue, heated garage!)  A total of 12 tons. I also find out the home has 6 bedrooms, 5 people living in it, and a total of 5200 square feet.  A quick estimation in my head, 3 finished floors, tall ceilings, I’m thinking in the neighborhood of 40,000 cubic feet. That’s a big home for rural Northern Minnesota.

The homeowner tells me the walls are spray foamed and the ceiling has blown fiberglass insulation in the flat ceilings, fiberglass batts in the vault. Looking around, there’s a lot of glass.  I’ll ask more questions about how the home was built later.  The home sits on a rural farm with expansive views of fields used to graze their 6 horses and 10 cattle.  Ah, another clue.  A hobby farm.  That realization leads to new questions.  I need to ask detailed questions about the outbuildings.  Are they heated?  How do they water the livestock in the winter?  And then another statement…they have chickens. Even more questions need to be asked, but I’m forming a picture in my mind of why the costs are high.

I’ve been doing energy assessments and audits, (an energy audit is an energy assessment with testing of the home), for more than 10 years.  I still see things that amaze me.  The guy burning his brother’s collection of girly magazines because he ran out of firewood.  The couple with 20 aquariums full of snakes, spiders and lizards, most with heat lamps, and then there’s the hobby farms.  Chicken coops with space heaters, heat lamps, and small water heaters designed to keep water from freezing, all for chickens!  The floating tank heaters that draw sometimes up to 1200 watts so that the water doesn’t freeze for the horses and cattle.  Tractors that need to be plugged in to an electrical outlet so that they will start during very cold weather.  Heated shops to store all the farming equipment and tools.  I’ve even been to a crop hobby farm.  These people were selling their vegetables at local farmer’s markets and co-ops.  This farm had 3 wells for watering the crops during the summer.

Getting through the hobby farm questions, I find they have two electric heaters for the horse and cattle water, they draw a total of 425 watts continuously during the winter and are costing around $40 per month.  The chicken coop has a pair of 200-watt heating lamps keeping the chickens warm during the winter.  Another $40 or so. And then there’s the tack room. This room, in one of the outbuildings, is heated with an electric wall hung heater.  A thermostatically controlled 5000-watt unit.  Electric heating is hard to estimate the actual cost.  I can calculate how much the heater is costing during the times its operating, but I can only guess at how often it is running.  The homeowner tells me the thermostat is set at 40°F.  I estimate a 20% run time and a cost of around $90 per month.  All these costs are for wintertime.  I see in my electricity usage data for this customer that their usage drops 2/3 during the summer, and 15-20% of the wintertime costs is for the livestock and chickens.  Part of the investigation solved.

Back to the home.  Looking at the electrical history, I see that the shoulder months, typically May and September are the lowest consumption months. About 1500 kW of power were used those months. (That’s more than twice what I consider “normal” for my area.)  I know the shoulder months are typically free of heating and air conditioning costs.  My assumption is this is the minimum electrical consumption for the home.  This is my next area to key in on.  My questions turn to how the homeowners live in the home.
5 people, showering, cooking and the rest of the normal household activities.  There’s an electric water heater on the general service rate.  I estimate that’s nearly 1/3 of the usage of the “normal consumption” for this home.  There’s one newer refrigerator and a couple older chest freezers. (The freezers are full.)  They have two coffee makers, a Keurig and a Bunn (mini water heater), electric range and double oven, television and gaming systems, typically lighting, (switching to LED’s as the old incandescent burn out), computers and the other normal household electric devices.  Oh, and the steam shower that’s used daily…another water heater.  There’re still the normal farming operations.  Working in the shop, an electric fencer, etc.… The farm is rural, there’s the well and on-site sewage treatment system which includes a pump.  Considering the number of people living in the home along with the appliances and electrical devices in use, I’ve been able to account for most of the 1500 kW usage.

So, where do I suggest ways to save on the general electricity usage and cost.  I first tackle the water heater.  For this family, I suggest allowing the power company to control the water heater, in return, the homeowners receive a reduced rate and because the heater only takes a charge in the middle of the night, the electricity consumption is also cut.  This program requires a larger than normal tank, at least 100 gallons and an increase in the water temperature, 130°F is suggested.  This allows for more cold water to be mixed in, helping the 100 gallons of hot water last longer.  This program typically cuts the water heating cost by 60%, sometimes more.
The remaining suggestions are all based on consumption reduction.  Use cold water for washing clothes when they can, limit showering times (sometimes tough with teenagers in the home), continue switching to LED light bulbs and turn off lights when a room is unoccupied.  Clean the backside and under refrigerators and freezers to help increase heat transfer and reduce run times.  I also try to give some education.  I encourage all homeowner to purchase a recording watt meter to measure the electricity consumption of various devices around the home.  I also instruct how to calculate energy use to dollars.  Hopefully they can then calculate some basic appliance energy usage and determine if there is any place to save (like the two coffee makers).

Next up is the home itself.  How is it constructed, can I estimate how tight the home was built, (blower door testing would be helpful but is an additional cost to the homeowner, most aren’t willing to pay for the test), what are the insulation levels?  Along with these concerns, I’m also thinking of health and safety.  Is there an elevated moisture level that may cause mold or other air quality problems?  In the case of this home, there is that heated, attached garage.  Heated garages are another area that is hard to estimate energy usage.  My climate offers very cold, snowy vehicles entering and exiting a structure with very large, often poorly air sealed doors.  Snow melting off these vehicles will raise the humidity level in the space.  Does that humidity end up in the home?  If humidity can enter the home from the garage, then carbon monoxide can also get in.  Another issue.  I include my concerns with moisture in the garage in my report, along with a few different suggestions on how to reduce the humidity.  My go-to number for heating an attached garage is between $50 and $100 per month.  This garage is heated with the geothermal hydronic system, which is also heating the basement floor.  Hard to accurately estimate heating costs of this space.

Back inside the home.  The homeowner mentions the floor is always cold near the sliding patio door in the master bedroom.  I break out the thermal imaging camera and can instantly see the issue.  Again, a blower door test would give me additional valuable information on whether the problem is with the sliding patio door or it’s installation.  I’ve seen the problems sliding patio doors can have.  This unit was made by a major manufacturer.  I suggest having a factory service team or the building contractor adjust the unit.  After that, pull the trim to determine the insulation and air sealing strategies and make any improvements possible.  Lastly, caulk the floor to door transition.  This will require carpeting to get pulled from the tack strips and then re-stretched.

Looking back at the electrical history, I see the highest consumption is during the dead of winter, over 7,000 kW resulting in a bill over $1000.  I’ve been able to account for roughly half the load.  This leads me to believe the remaining costs are heat related.  It’s a big home, but $500 seems a little too high, especially with ground source heat pumps as the main heat source. The units would have to be operating nearly continuously during that time period to rack up a bill that high.  This leads me back to how the home was built.  The homeowner doesn’t remember the insulation thickness under the concrete slab in either the basement or garage, or how the slab edges were addressed.  There’s no place I can see this insulation without a jackhammer. These areas could be leaking heat directly into the earth or trying to heat the outside at the slab edge.  I also don’t know how tight the home is.  The walls are spray foamed, I must assume they are air sealed better than most, but the ceiling.  With no testing, it’s my best guess.  I ask a couple more questions.  Is there any moisture that builds up on the windows during the wintertime?  The answer is “no”.  My next question, I see there is a heat recovery ventilator (HRV) in the basement, do you operate that?  “No, it makes areas in the home uncomfortable when its cold outside.”  Ahhh, natural air leaks.  Low humidity occurs when there is a high natural air exchange rate between inside and outside the home during cold weather.  Just to confirm, I take out my Extech Humidity/Temperature Pen, 30% with a 40-degree difference between inside and outside temperatures.  As the temperature drops, so will the interior humidity level. Air leaks will also affect the heating costs.  My best guess!

The assessment visit is finished, I then have a conversation with the homeowners discussing some of my findings.  We exchange pleasantries and I leave.  I will continue to think about what I saw during the 45-minute drive home, sometimes jotting notes as I formulate my thoughts.  Then there’s the 2 hours spent typing the report.  With over a thousand reports typed, I have an extensive copy and paste section which saves time.  The report hits the mail and another assessment complete.

I love my job!