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About a year ago I met with Gabriela Martin for coffee (outdoors, socially distanced and masked up). Gabriela is the Zero-Energy programmastermind and manager at the Illinois Clean Energy Communities Foundation. Several school buildings used PHIUS standards to meet the ICECF zero-energy goal. The projects that receive ICECF funding only receive the full grant when the project actually meets the zero-energy goal, which requires detailed monitoring of actual performance. Gabriela tells me about her findings, sighs… says the envelope is next to perfect, doing its job but the systems…a whole other story. Almost all the awarded buildings have missed the target so far. The culprit: the performance of the mechanical systems.
Mechanical…what do we mean by that and why does this topic warrant an entire summit in and of itself? I think of mechanical as encompassing balanced ventilation, space conditioning, hot water and electrical…in short all active systems and their components needed in a building. In terms of achieving, mechanical systems are the weakest link.
This is due for two main reasons.
1. Claimed systems efficiencies often are optimistic.
2. Installation is often wanting, including distribution, significantly reducing whole systems efficiencies.
Neither of these are necessarily anybody’s fault. But it points out that existing mechanical systems design for inefficient buildings: Designers and installers over-compensate for inaccuracies and potentially bad installs by designing and installing oversized systems allowing for redundancy.
Belts and suspenders.
Passive building requirements are different. The tolerances for inaccurate assumptions are much smaller. Passive buildings fundamentally act differently and need differently calibrated components to account for comfort.
In absence of systems and equipment designed for low-load buildings, most design teams are left to improvise. They assemble components that might not typically be used in conjunction in conventional construction…they have to make do with what they can find on the market, improvising solutions that are not ideal for passive buildings.
We need and deserve better!
• We practioners need to keep pushing to build the market to help manufacturers justify new products that meet our needs. We need to be clear about what we need.
• We need manufacturers to hear us, to offer help creating solutions from existing products, and to eventually respond with new products for low-load buildings.
We want the PHIUS Mechanical Summit to accelerate our efforts; to advance the conversation between the designers, manufacturers and installers.
Policy makers are taking notice, and that’s great. But to fulfill the net Zero promise, it is clear, we need the larger HVAC and other manufacturers to enter the scene, and in short order!
Passive building, low load systems design can be the economic key to mainstreaming zero energy buidlings. Its mechanical systems can be minimized and designed in an integrated way, offering “plug-and-play,” it would yield a significant reduction in terms of first cost, operational cost and maintenance. This could dramatically change the economic feasibility of zero energy buildings and facilitate it going mainstream.
During the first CPHC classes in 2008, I used to describe how we conventionally build our houses. We build the same envelope in all climates (usually with scant attention to insulation and air sealing), and then we put a giant furnace into it to keep us comfortable. The size of that furnace is variable, depending on the climate, it comes in big or huge. Energy was not a prime concern.
In a passive building we turn that idea on its head. What if we made the shell of a building do most of the work instead of the furnace? We’d make its shell match the climate when insulating it and air-seal it. We then make sure it is right-sized so that the small “micro-load” system has no trouble keeping the space comfortable no matter where we build. The micro-load system of a predetermined size would also assure that we meet our carbon reduction goals and reduce our carbon footprint. It would act like cruise control to stay under the emissions speed limit.
What if the envelope is designed to do the heavy lifting, to fit the micro-load system instead of the other way around? That was the initial ground-breaking idea brought forward by the passive house pioneers in the 1970s in response to the oil embargo in an effort to reduce total energy consumption by about 70%, reducing the micro-load mechanicals to only about 15% capacity of a regular system! This idea is a BIG DEAL! 85% in reduction of systems size!
We on the building and design side have been hampered by the lack of low load systems on the market specifically designed for the changed dynamics in low load buildings. Mechanical engineers often are unfamiliar with passive building design. Manufacturers have not yet responded to the emerging passive building market’s unique demands—to now, the market wasn’t there. But that is changing.
Growth has been driven by creative design teams that often make do with components designed for conventional buildings. But in terms of maintenance and scaling, the status quo won’t do.
We need solutions that account for balanced ventilation, loads, load relationships and distribution requirements in passive buildings. Such packaged solutions are emerging, driven by small companies, that can make progress only very slowly but it is a positive sign. What about joint ventures?
That’s the kind of question we’d like to address at the summit, in addition to sharing lessons learned about how existing equipment has been used to solve the passive mechanical puzzle.
We’ve come a long, long way since I built my own passive home back in 2003. But to get where we want to go: mainstream passive building to achieve Zero, we need to tackle the mechanical issue.
Let’s do it like we always have, together.
Please join us during Earth Week for the PHIUS Mechanical Summit.
Each day of the Summit will cover one of four main topics in an effort to bring further awareness to what components and practices can help create a solid mechanical system across different climates:
Day 1, 4/19: Design Principles / Best Practices
Day 2, 4/20: Gap Solutions / Tools
Day 3, 4/21: Products / Systems Designs
Day 4, 4/22: Earth day: Zero Energy and Carbon / Electrification
PHIUS will offer both pre-recorded, on-demand content and a live panel Q&A discussion for each day of the Summit. The experts featured in both mediums will cover a large segment of passive building practice areas. Attendees will hear from those involved in product development, systems design, energy modeling, HVAC installation, and quality assurance.
Kat
