Once you have completed a Passive House project the next logical question is how did we do over the long haul? How is our building performing? Mark Rosenberg is fond of saying there are no net-zero buildings only net-zero users and we have come to realize just how true a statement that is. The problem is that without monitoring the equipment in the building, it is virtually impossible to tell how your building is performing. We have developed a relationship with the owner of the first Passive House we designed and have visited a number of times since she moved in. This house is occupied by someone who, while very fond of the house and in love with her low utility bills, is far from a net-zero user. When we walk into the building every room has a TV that is on and streaming music; Halloween holiday lights, illuminated figurine displays, electric air-fresheners, electric blankets, hot dog makers, crock pots, and electric counter-top grills and are just a few of the plug loads that adorn the house. Without the ability to separate data from the plug loads of the occupant, from data for heating and cooling, we are unable to really understand how well our building is performing. We are unable to give it a realistic EUI and we are deprived of the knowledge that can help us really improve performance in future projects.
Tim MacDonald, of Onion Flats, has a great story about three Passive House Townhouses that he completed. When he looked at the utility bills for all three there was a wildly different pattern of usage for each. One was low, about what he expected, one was high, and one was off the charts. After investigating he realized that while the first unit was occupied by someone who didn't waste energy, the second unit was occupied by a smoker who left the door open when he was smoking throughout the year, and the third unit was occupied by someone who was running a neighborhood laundry service out of her unit! Users impact energy use almost more than anything else!
We need to be able to develop a benchmark for the projects we complete. In more complex commercial projects this becomes even more relevant. At MDH we had a high electric bill toward the end of construction. It was impossible for us to tell what the source of that energy usage was. We could imagine several plausible reasons why the energy bill might have spiked during construction, but we were not in the position to definitively understand why this happened and report that back to our client. It is important to stay focused on the performance of completed projects; their performance over time is the most important issue to understand. Carbon emissions are really represented by a building's performance, and not by metrics measured at the end of construction or in the abstraction of an energy model.