Yesterday I had our second conference call with Zero Energy Design who is performing energy modeling analysis on the 100K House. Yes, they changed their name since our last meeting. They provided a list of suggested energy improvements to the home with accompanying savings that would be realized over a code built home per year. I uploaded the spreadsheet to our documents page and an image of it is also shown below.
Note that the savings shown for each item is the estimated savings in one year of utility bills over a similar home built to code (IECC 2006). Each item does not take the other improvements into account, so ultimately the savings for each line item will be less in the final energy model that takes into account all improvements. Lastly, two versions of the model were run – one with A/C and one without.
- Beefing up the SIPs further was not recommended. We currently have 6.5″ wall panels and 10.25″ ceiling panels spec’ed out and ZED recommended staying with the same wall panels and reducing the ceiling to 8.25″. The model only takes into account the R value of the different SIPs but I was surprised to see how little effect the higher levels of roof insulation would make.
- There is a decent difference in the window types we are evaluating, but we will need to determine whether the significant cost premium for the Thermotech windows will pay off or if it is better spent somewhere else.
- Insulating window shades seems to be a very good investment given the relatively low cost to essentially double the insulation value of the windows.
- Window overhangs don’t have as much effect as I thought they would. The negative value with no A/C is because some sun will be blocked in the winter that would reduce the heating load while there is no reduction in A/C costs in the summer, because there is no A/C. This does not mean they will not be needed in the summer, as we need to cool the home as much as possible via passive methods.
- An efficient boiler seems to be the way to go for heating both the domestic and radiant water. It even outperforms the popular tankless units being used today.
- Amazing what a difference a simple $20 programmable thermostat can make!
- Solar thermal is looking like a good investment, especially with the boiler and tank setup and the possibility of eliminating A/C.
- CFL’s are more efficient that LEDs. Who knew? ZED says this is a common misconception due to the amount of LEDs that are needed to match the light output of CFLs in a similar spectrum of light that is pleasing to the eyes.
The next step is for ZED to plug the items we have chosen into their detailed energy model to determine the amount we can expect to save over a code built home. We did not get into specific models of equipment to be used too much in the meeting, but that will all be included in their final report. I can’t wait to see some pretty charts that clearly illustrate the predicted energy savings of the home. I will be posting in more detail on some of my thoughts on each of these line items also over the next few days.
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