What Is The True Cost of Ownership of a Passive House?

The Short Answer
We define true cost of ownership as the total payment per month for energy, mortgage principal, interest, and taxes.  It turns out that this house will be considerably less expensive to own than an average comparable house of the same size. The bottom line monthly cost of ownership for this house was lower—all due to the lower energy costs. As energy costs rise, the difference becomes more significant.

This is spelled out in greater detail below. While we did our best to use conservative numbers and historic cost data, we cannot guarantee these numbers.  For those who would like to review the spreadsheets that produced these numbers, please contact me at david@greenhaus.org and I will be happy to share them and to receive input. All comments appreciated in the comment box below as well.

Comparison with an average house of the same size…
The table below compares purchase of our Passive House against purchase of an existing Bethesda house of the same size and features, but with only average energy performance. In both cases we assumed a purchase cost of $1,688,000. In both cases we assumed a 20% down payment with a 30 year fixed rate mortgage at 4.85% interest.  Payment includes principal + interest + tax + insurance.

 We looked at the monthly cost of ownership (note payment plus energy cost) for each house in three separate scenarios assuming differing increases of the annual cost of energy, starting at 1% and ending at 5%.  As a point of reference, annual energy cost increases over the past 30 years have averaged around 5%. Our results are shown in the table below:

Conclusion:

The Passive House is less expensive to own from the very first month, even with its incrementally higher first cost. As energy costs rise, those savings become significantly larger.