BRING ME DATA
For those Passive House skeptics with no faith, we’re now starting to collect the hard data that may convince you. Our Cottle NZE Passive House is giving us exactly the type of feedback every Design Build company should want: great performance. We’re fortunate to have the Davis Energy Group monitoring and collecting this data. Last week they submitted the following graph as part of their report to Pacific Gas & Electric Company – the entity funding the research.
Here’s a brief summary of what it shows:
· The green line is the outdoor temperature, showing one of our hotter weeks this past June when it reached over 90oF for two of the days.
· The red and orange lines track the indoor temperature for both floors of this 2-story house. We have 10ft ceilings downstairs and 9ft upstairs, so quite a big height difference with minimal temperature stratification.
· The grey ‘city’ profile at the bottom follows the fan power for the nightbreeze ventilation system.
So what does this all mean - other than we’ve built an awesome building?
· The minimal indoor temperature swings between day and night prove that Passive House insulation levels do keep you COMFORTABLE, no matter how hot (or cold) it is outside.
· The small differential (AVG < 1deg.) between the upstairs and downstairs temperatures means that STACK EFFECT is no longer an issue in a Passive House. (So you architects drawing those weird arrows that change from blue to red should probably re-think that graphic if you’re building to PH insulation and air-tight levels.)
· Our Night Breeze night ventilation cooling system is effectively working at a summer average EER of 49.6 (see chart) – a previously unheard of level of efficiency over four times more efficient than standard AC cooling systems. It easily and effectively ‘dumps’ the small amount of interior heat built up during the day at a very low cost.
Essentially this data shows that the complete Passive House package of good building insulation, great air-sealing, careful orientation and shading, combined with efficient systems ensures that EVERYTHING works better. Now that’s data we can crow about!