Balancing the energy, volume and use of a high performance building is a great challenge. It does not just have to be a simple box, yes that is simple and efficient but it doesn’t have to be. It takes a little more work and troubleshooting but it can be achieved, to an extent as I learned with the 5x20x15 house.

After running through all the systems I wasn’t able to achieve the passivhaus certification. At first I thought I was inputting wrong information, but after multiple tries, weeks of trouble shooting, back and forth with passivhaus forums, I still couldn’t figure it out.

With the help of Tim Delhey Eian from TE Studio in Minnesota, he confirmed my case, it wasn’t wrong information from the user, but the site conditions did have there limitations. I guess I started with a very hard problem, but that’s the best way to start! Facing east, with no windows on the south or west, was a major hurdle.

After we spoke and did some troubleshooting, we finally came to the conclusion that Passivhaus Classic 15kWh/(m2a) was not achievable, but Passivhaus Low Energy Building 30kWh/(m2a) was.


The first issue as I suspected was the external surface area to internal volume ratio.

The first one has an A/V of 6.75, which means you have more external building surface to internal volume, this can affect the energy balance. More area for energy to escape to the amount of energy you can actually put in the volume. The other end has an A/V of 0.39, more volume to surface area, more internal energy to the energy that is lost from the surface area.
I confirmed my data, the 5x2015 house has a very bad A/V ratio. The majority of energy lost is from the external walls.  Another ratio to keep track of during the design, external surface area to treated floor space.
Here you see how the form factor plays a role, the more complex, the harder it will be to balance the energy lost and gained. Not to say that a simple box is the only way, just another parameter that you need to think of. The lower the ratio, the better.

PassivHaus has different levels of certification, the Low Energy Building  certification has a maximum energy demand of 30kWh/(m2a).
As you can see, the building has met the standard. The 30kWh/(m2a) is the energy needed to heat the building.
Overall  the external surface area is a major energy loss, the glass roof systems help by all the solar energy gained.

All great lessons learned.
Mark