Over the last couple of weeks we have switched the house from summer cooling mode to winter heating mode.
I was going to avoid switching the heating system on as long as I could. It occurred to me though, that I am more interested in measuring the energy our house uses to keep a comfortable environment (for me, Kate and our guests) than seeing how cold I can bear it.
It also took us a bit of time to get the hang of the new system.
We have a simple thermostat for the infloor heat in each zone in the house with two exceptions.
Each of these has a sensor in the floor that measures the temperature in the floor slab.
For the zone including the great room upstairs and the game room downstairs, we have a programmable Honeywell thermostat.
After some adjustments and tweaking, these are set up to first call for the infloor heat, then the warm air if needed.
The radiant heat is the most efficient heating method (besides the passive heating from the sun). It is also a very slow way to heat.
If the temperature on the thermostat is more than two degrees below the ambient temperature, it will call for hot air from the Air Handler, which is less efficient but also much quicker.
The concrete slab downstairs takes even longer than the gypcrete upstairs. So downstairs, we have been advised, we have set the temp in the gameroom at a comfortable level and simply leave it there.
This is far different than what I was used to doing, but the concrete requires so little energy to maintain the temperature, where it takes a bunch to raise it or lower it, that it makes more sense to do it this way.
Each of the smaller zones we have set to different temperatures. The master bathroom is a couple degrees warmer to give us a very comfortable floor for bare feet ;), likewise the excercise room downstairs and the powder room/laundry room and a bit cooler.
We are playing around with the points we set for each zone as well as the programming for the temperatures in the greatroom. I expect as we get into a more seasonable chill we will make some further adjustments.
Our first snowfall (that stayed on the ground for any time) gave us a beautiful coating of snow on the recessed boulder wall. Unfortunately, it was a very grey day and my photo doesn't do it justice.
We also just had our final energy testing done a couple days ago and we came through with flying colors!
Pat O'Malley of Building Knowledge was out to test the amount of air various ducts were moving under normal pressures, and when the house was pressurized.
This is done by setting up a "blower door test".
What a blower door test does is to lower the pressure inside the house compared to the pressure outside.
This will show any leaks in the house through various measurements.
Some of the tools used to make those measurements are a infared camera (FLIR), devices to measure the airflow (if any) coming through ductwork both at different pressure gradients and hoods that cover a air register and measure the flow compared with the airflow at the air handler.
These blower door tests are extremely useful in any house, just to find where the house is loosing energy. Often, this can be easily improved. Many utilities offer discounted, or even free 'Home Energy Audits' which can help you discover where you can make improvements.
More details about blower door tests can be found at this link.
Our overall certifications are still waiting on some necessary calculations and paperwork. I hope to have them all by the end of the year.
In short though, one of the main peices of data that we get from the testing is the houses ACH, which stands for Air Changes per Hour. The ACH is followed by a number which indicates the pressure difference produced by the blower door during the test. The standard for these is 50 Pascals, so the term used is ACH50.
A typical house built to code without any special care taken on sealing the house is in the 7-10 ACH50 range. This means the amount of air the house holds is moved out of the house 7 to 10 times every hour.
A house that is built with a reasonable amount of care can reach 4-5 ACH50 fairly easily.
We managed to reach 0.83 ACH50!
This number though, is only a part of our score in some of the certifications we are shooting for, so we won't know the final numbers for a few weeks or month yet.
The preliminary HERS (Home Energy Rating System) score we received was -29, with the results of the test, and the fact that we installed a more efficient ERV (this recovers some of the energy/heat from air exiting the house) than first planned, may lower that number, but just by one or two.
This is based on a house built to todays code being rated at 100. The lower the number the better.
The reason we have a negative number is that the HERS doesn't take into account energy being used to power vehicles. Since we want to power both of our cars with the energy our solar panels collect, we end up with a negative number.
The final cabinets!!!!
Well, we found one more spot we could put in some more cabinetry.
Julie, with Twin Cities Closets, once again came to our rescure with a very creative solution to our question for her.
Since we almost always enter the house through our link between the garage and the house, we thought a bench would be convenient out there.
Storage for some shoes would also be nice.
Primarily though, we though a gardening bench here would work well since we have the door directly to the back yard right there.
We also wanted a space to store brooms, mops, etc.
And of course, we needed it all in the small space.
Julie didn't bat an eye;)
She got down to work, and sent us a design. We made some minor changes, a couple of guys from TTC came out and installed our new bench/broom closet/gardening bench in a single day.
I frankly can't believe how useful that space is now. Next summer that will be getting even more use!
The inverter we were having some minor issues with has been rewired which should take care of the last of the issues. Unfortunately, due to the lower angle, and rare appearance of the sun in winter, I am thinking we won't be stressing the system until spring.
Next month, if I don't have anything to report earlier, I'll give an update on our first three months of tracked power use. November has been so warm here, it really isn't a fair test of "winter". So far though, it is going really really well.
Thanks for your time!
Mark really doesn't like to talk about himself, the house is much more interesting.