Producing energy optimised designs and construction assembly details for high performance buildings is too urgent and important to fight over who’s name gets on the wall plaque. In wanting to accelerate wide adoption of a significantly higher than building code energy performance standard for the North American market, the Passive House Institute United States (PHIUS) tasked a volunteer Technical Committee in 2011. They have just released their highly anticipated Climate-Specific Passive Building Standards in conjunction with Building Science Corp through Building America.
Called PHIUS + 2015 , the technical document aims to find the “climate-specific sweet spot where aggressive energy and carbon reduction overlap with cost effectiveness” as opposed to the ‘one-size fits all’ PHI approach which highly respected industry professionals like GBA’s Editor Martin Holladay openly muse if some of the Passivhaus requirements are logical perhaps even arbitrary .
In a nutshell, the changes proposed for the new PHIUS standard follow the three pillars:
1. The air-tightness requirement was reconsidered on the basis of avoiding moisture and mold risk. The proposed change is from a limit of 0.6 ACH50 to 0.05 CFM50 per square foot of gross envelope area (or 0.08 CFM75). This allows the airtightness requirement to scale appropriately based on building size.
2. The source energy limit was reconsidered on the basis of the global CO2 emission budget. The following changes are proposed to make the scoring more fair and the calculation more accurate:
- Change to a per-person limit rather than per square foot of floor area, for residential projects.
- Correct the source energy factor for grid electricity in the calculation protocol to 3.16, consistent with the US national average.
- Adopt lighting and miscellaneous-plug-load defaults at 80% of the Residential Energy Services Network (RESNET) standard.
- Set the source energy limit to 6200 kWh per person per year, tightening to 4200 within a few years TBD.
- Apply the limit to the source energy calculated net of the estimated fraction of onsite photovoltaic (PV) or other renewable electricity generation that is used onsite as it is produced. This accounts for PV the same way solar hot water is accounted for.
3. The space conditioning criteria were reconsidered on the basis of economic feasibility. The proposed change is to:
- Shift to mandatory thresholds on annual heating and cooling demands and peak heating and cooling loads, climate-specific to a project’s location, which aim for a near-optimal “sweet spot” with slightly more energy savings than BEopt’s calculated cost optimum. This ensures efficiency measures will be reasonably cost-competitive, while providing some increased resilience benefits.
- Adopt a simplified reference floor area – an inclusive interior-dimension floor area.
‘Passivhaus’ vs ‘Passive House’?
Influential eco-starchitects like Daniel Pearl of l’Oeuf have come full circle after 20 years of practice in admitting that the Passive House approach is where we need to go as a society in designing and building the next generation of buildings. The facts remain:
- Germans and Americans don’t look at payback in the same way and they’re philosophical approaches to construction in general are an ocean apart.
- In the EU, and Germany in particular, very few homes are actually certified as “Passive House” by PHI. There’s no need, home owners don’t need the plaque, they just want the performance.
- Climate change is here and there’s an urgent call for higher building efficiency; that means the price of building materials and construction techniques needs to be ‘more’ competitive and the ‘one-size fits all climates’ PHI approach may be too rigid.
- The great irony in all of this infighting is that even PHI is adding water to the wine with the introduction of three new certification standards ostensibly to ‘certify’ more homes in America.
- Meanwhile, NESEA’s Pretty Good House makes compelling arguments against PHI’s dogmatic approach if we want rapid adoption of a significantly higher performing homes to be built now.
The elephant in the room
Here’s what I know, German architect Katrin Klingenberg has been singularly focused-on and doggedly pushing the PH approach in the USA and Canada since the early 2000′s because she believes there’s an urgent call to action in building and retrofitting better. I’d attend most of her talks at Affordable Comfort Inc. and in the early days the audience was small, but over the years I watched her build and nurture an audience interested in what she had to say. This is well before a divisive Canadian helped trigger the current North American vs European schism, the result of which, is confusion in the marketplace and unnecessary division. Ironically, it may eventually might lead to wider adoption of a high performance standard that swings conventional builders over to the sustainable, high performance side and away from prescriptive code minimums.
The infighting in North America between the euro-centric approach versus the dynamic ideas offered by PHIUS does a huge dis-service to the rapid adoption and implementation of the principles of Passive House – both produce incredibly efficient buildings. I certainly understand the allure for American builders and architects wanting to differentiate their brand as “the sexy German sports car equivalent”, but let’s not forget the huge benefits of the old “Made in America” slogan.
The duplication is most hurtful in that both hold separate conferences in the US that are timed to divide allegiance. Thankfully, the Canadian NGO PBC has been steadily and magnanimously trying to push for an inclusive adoption of the principles of Passive House irrespective of the certifying agency, be it PHIUS or PHI.
The mudslinging goes on and until the kids can play in the sandbox together, they will be seen by the status quo as what they are – building nerds who are willing to split hairs over a few kWh, the messy exclusion of floor cavities and who’s name gets on the wall plaque. The world needs unity on tackling the effects of climate change – let’s build better with or without a certification, now!