Yesterday I received the final report from Zero Energy Design with the results of their energy modeling. We put out a joint press release this morning but I thought I would include a bit more detail along with some of the pretty charts that ZED made here on the blog.
ZED provided charts and analysis on three different models for the home. The first is the “Baseline” which is how a home built to code of the same size would perform. The next series is called “ZED Improved” and represents the features we plan to put in the base 100K House that will fit in our budget. The final model is called “ZED Optimized” and includes two optional upgrades that the home buyer could choose to have us install at an extra cost prior to them taking ownership of the home.
Before getting into more detail, here are two summary charts that show the results of the modeling.
The ZED Improved version that we will be going with on the base home will use 43% less energy than the Baseline code home. Zero Energy Design also remarked that the average existing home performs over 30% worse than a new code home built today. This means that the base 100K House should be 2.5 times more energy efficient that the average existing home.
The ZED Optimized version uses 8% less energy than the ZED Improved and 48% less than the Baseline model.
Three Model Comparison
Baseline Code Built Model
There’s not a lot to say about the Baseline model. Code homes have insulation values of R-13 in the walls and R-38 in the ceiling. They use standard windows, HVAC equipment and appliances that are not energy star rated. Below is the breakdown of monthly energy consumption by use. Heating is in red, lighting in yellow, hot water in orange and appliances in green.
ZED Improved Model (Base 100K House)
Some of the features that the ZED Improved model include are as follows:
- SIP walls at R-24, SIP ceilings at R-42 and a tighter envelope than code
- Energy Star windows by Pella Proline with a U-value of 0.34 and Solar Heat Gain Coefficient of 0.28
- Programmable Thermostat
- A 90% efficient gas water heater
- An Energy Recovery Ventilator (ERV)
- A solar thermal system with an 80-gallon tank and one solar panel
- Compact Fluorescent Lighting
- Energy Star Appliances
I have included a few more charts to show the performance breakdown for this model in a bit more detail below:
One thing to note is that as the home gets more energy efficient overall, the appliances really take up a large portion of the overall energy consumption. This is even without our TV’s, stereos and PC’s in the mix so you can start to see how much energy we still consume outside of heating and cooling. No matter how efficient a home is, it will still take a sizable renewable energy source like solar or wind to bring a home down to zero energy/carbon levels.
ZED Optimized Model
The ZED Optimized model adds two upgrade options to the home:
- An additional solar thermal panel to double the impact on the hot water energy consumption
- Cellular thermal window shades on all windows to double their R-value
We put these into the optimized model because they just could not be fit into the budget of the base 100K House. There is an outside chance that we can fit the second solar thermal panel into the budget due to federal incentives, but we will leave the window shades out. The buyer can decide if they would like to implement and also be able to choose the style and level of insulation they would like to have installed. See the final chart below for details on the Optimized model.
That’s it for now. I am off to a budget review meeting. We’ll try to provide more details on the equipment we decide to put in the final house over the next week as we nail this down with our HVAC installer and the rest of the team.