Chicago Regulation Change Provides Opportunity for Phius Professionals

Al Mitchell

Al Mitchell

Phius Technical Staff Member Al Mitchell wrote this week’s blog post, which discusses the recent change in regulations related to coach houses in Chicago, and how designing these new buildings to Phius standards is a win-win for all parties.

The City of Chicago has lifted a nearly half-century ban on accessory dwelling units (ADUs), opening up a door for some people to build additional units on their property. The pilot program for ADU construction pertains to rentable units, occupiable by relatives, tenants, or even to be used as additional space from the primary home. There are two types of ADUs acknowledged by this regulation: a detached dwelling unit, such as a coach house or apartment on top of the garage, or a conversion unit, such as a built-out attic or basement.

However, there are a handful of caveats to consider. First, the allowances for ADUs, whether coach houses or conversion units, are limited to select pilot zones. There are five pilot zones: North, Northwest, West, South, and Southeast. These zones cover portions of 25 of the 77 Chicago community areas. Each area has a few special requirements for different types of ADU. For example, the North and Northwest zones can have a coach house built on the property before a primary house is built, while the other three zones require a primary house to be built on the lot before a coach house can be built. In the West, South, and Southwest zones, buildings must be owner-occupied in order to add a conversion unit. All ADUs in Chicago are to be rented for a minimum period of 1 month, and there is a requirement for a certain number of affordable units on larger properties where more units can be added.

 

Blog Pic 1This offers a great opportunity for people to add value to their property, create flexible living spaces (especially to take advantage of the benefits of multi-generational housing) or build a unit that can provide additional income for the owner while providing right-sized, cost-effective housing for another person. Approximately 70% of the lots in Chicago are 25 feet wide and face broadside south, making the applicability of this format broad. The aim of this blog is to make the case for building these newly allowed accessory dwelling units following the Phius passive building standards to create comfortable spaces, save energy and operational costs, and provide spaces that can weather inclement weather conditions, especially during a failure of space conditioning.

Analysis

Conversion units like the ones proposed in Chicago, would likely require a complete building retrofit to achieve the maximum cost and energy saving potential. This study is going to focus on detached coach houses, of maximum permitted dimensions. This comes at an apt time for Phius, as 2021 has marked the release of a user-friendly and streamlined prescriptive compliance path, as well as the performance target curves have been reworked to include allowances for small living spaces (in response to the tiny home craze).

Looking at coach house potentials, four cases were selected for evaluation. Three of the cases represent a single-story unit, one in the place of the garage, one pushed forward with open parking on the alley, and one built on top of the garage. The fourth case is a two-story coach house with no garage. The smaller units are studios, with no bedroom considered, one occupant, and the two-story coach house has one bedroom and two occupants. The standard kit of appliances is a dishwasher, refrigerator, and an induction range. Electric resistance water heaters are used in the base cases and a split heat pump system provides space conditioning.

The base cases follow code minimum constructions and windows per IECC 2018.  An envelope airtightness of 0.31 CFM50/sqft was used to match typical construction. The Phius CORE Prescriptive Path follows the prescriptive requirements per Chicago – Midway airport, and uses the default airtightness of 0.04 CFM50/sqft. The prescriptive path windows are whole window U-Values, and are set based on the required prescriptive comfort standards. Per the water heater efficiency requirements, the water heater was upgraded to a small heat pump water heater. The performance path uses 0.06 CFM50/sqft as the required airtightness metric, and follows the same window set as the prescriptive path. A heat pump water heater was used.  The other opaque assemblies were backed off from the conservative prescriptive path to meet the required calculated targets. Please reference the table below for the envelope performance specs in the study.

 

Case Wall R Roof R Slab R Window-U Airtightness CFM50/sf
IECC 2018 18.4 44.0 10.6 0.3 0.31
Phius 2021 CORE Prescriptive 40.0 71.0 21.6 0.16 0.04
Phius 2021 CORE 26.8 52.0 17.2 0.16 0.06
Blog Pic 2

 

Conclusion

The cases designed to Phius standards prove to reduce the space conditioning loads significantly, as shown in the Space Conditioning Results Chart. These outputs are specific per area, making it easy to compare different building sizes. Per the Source Energy Chart, the Prescriptive and Performance averages save 35% and 30% respectively. These source energy savings directly reflect the anticipated savings on an electrical power bill for the tenant of these coach houses.

Coach houses built to these passive building guidelines project significant energy savings that will directly benefit the occupants of these buildings, on top of the other comfort and passive survivability (what happens during a power failure – stay tuned for a part two blog). The required upgrades to meet the performance path is principally based around better windows and airtightness, saving on other insulation requirements per the prescriptive path. 

Blog Pic 3

The Phius Difference: Custom Energy Design Targets for Heating and Cooling — The Key to Zero

Katrin Klingenberg -- Co-Founder & Executive Director, Phius (Passive House Institute US)

Katrin Klingenberg — Co-Founder & Executive Director, Phius (Passive House Institute US)

The Klingenblog’s namesake, Katrin Klingenberg, wrote this week’s blog, examining custom energy design targets and how Phius’ approach to them sets the organization apart in the quest for Zero.

Designing zero energy and zero carbon buildings today can be cost effective if guided by the appropriate targets for investment in efficiency first. These targets are cost-optimized limits on heating and cooling loads.

The limits on heating and cooling loads are set to guide the design to a cost-optimal investment in passive conservation strategies: insulation (the appropriate amount, properly installed), dedicated continuous air, water, and vapor control layers, mitigation and avoidance of thermal bridging, high-performance windows (with appropriately tuned solar gain) and dedicated balanced ventilation with filtration and energy recovery. These principles ensure building resilience, health, comfort, safety and durability.

The cost optimization to set the targets focused on achieving the highest source energy savings (relative to a code baseline) for the least total cost (including the up-front cost of energy-saving measures, and ongoing operational costs). It factors in the cost of materials and the cost of energy supply in each particular region to calculate the sweet-spot. At some point, up-front conservation measures don’t pencil, and that’s when any additional investment should shift to active conservation strategies or active renewable energy generation systems.  These climate-optimized, project-specific targets for thermal performance define the cost-effective sweet spot on the path to zero.

The thermal performance targets are known in the industry as “Annual Heating Demand” and “Annual Cooling Demand.” They are expressed in kBTU per square foot per year or — in the metric world — in kWh per square meter per year. They are, in concept, similar to the Energy Use Intensity (EUI), but refer to the delivered heating and cooling energy required by the building. These annual space conditioning demands can only be met with passive measures and dial in the thermal performance of the building. Once those are met, a conservation-first focused total energy budget is set to guide investment in active measures. This limit is also project-specific, and can be expressed in the EUI we are all familiar with — the amount of energy used by a building per unit of floor area per year, including space conditioning and all other energy uses. That EUI can be converted into an emissions equivalent as needed to determine offsets needed to achieve zero carbon. Voila! It’s that easy!

Phius is the only building certification program that has developed such design and certification targets. They are available on the Phius website in an easy-to-use calculator. Choose climate, enter building square footage and occupancy, and you get your optimized design parameters! They are also built into the easy-to-use design and certification tool, WUFI(R)  Passive.

Before supercomputing, managing such a complex, dynamic system of variables to generate custom targets as a designer was impossible. The task of energy optimization was handled by specialized engineering firms doing the modeling — a costly and external process. Small budget projects such as single-family and small multifamily projects could not take advantage of it. Even larger projects often took the prescriptive path to eliminate the cost of custom optimization. 

Today, the reliable and detailed accounting of emissions in the building sector is necessary on a per-building basis. Many cities have passed climate action plans with extremely specific emissions reduction targets to meet over the next few decades. The Phius standard now provides an easy-to-apply, cost-effective design, and certification methodology alongside accurate accounting of carbon emissions for any building in the building sector.

With some training, architects can now easily perform these calculations themselves and build it into their design workflows right from the beginning, making sure their design is on track from start to finish.

The framework for the Phius standard today was conceived in 2015, updated in 2018, and refined again in 2021. Many municipalities have leaned on and incentivized the Phius framework to meet their climate action plans. At the forefront was New York State Energy Research and Development Authority (NYSERDA) in the State of NY. They designed a proof-of-concept program early on called Buildings of Excellence. The agency now offers cost and performance data for representative groups of completed projects using varying techniques for low energy design and accounting.

C3RRO, a third-party consulting firm under the leadership of Florian Antretter, has graphed the NYSERDA cost and measured performance data for various approaches and graciously made it available to Phius for publication. The results are proving the concept. 

Graph

As envisioned, the Phius Standard, design, and certification methodology has led to projects that not only perform the best, but are also constructed at minimal additional upfront cost. (PHI projects that use a single target for heating and cooling limits in all climates also perform reasonably well but are more expensive to build).

The new comprehensive guidebook explaining the Phius Standard design and certification methodology is now available here.

We are well on our way to (Phius) ZERO emissions!

Green/Blue Roofing System Question Answered

 

GWPhius Senior Scientist Graham Wright weighs in on an interesting proposal for a green/blue roofing system and its feasibility for use on a Phius project.

The Question: “…The design team is considering a Green/Blue roofing system. Some of these systems / designs show rainwater being stored underneath the continuous insulation on the roof. We wanted to run these design concepts by you to understand what questions we should be asking and what information we should be gathering in order to model this, whether you have encountered this and have thoughts on how to model / approach this, and/or whether we should steer away from any of these designs altogether.”

The Answer: As far as I can tell, Green roofs and high insulation are not compatible, or, this is a research area.

The concept shown has only a thin layer of insulation. The Opti-Green system in the WUFI database is about R-3 overall. This research paper from 2012 looked at an R-22 roof.  

Green-Blue Roof Graphic

So, first thought: you probably could not do a large area of this and hope to meet the energy targets. It might be OK to experiment with it in a small area. They should ask if what is being proposed has any track record. Has this ever actually been built before in this climate?

Second thought: There is also clearly a tradeoff with the insulation positioned where it is. On the one hand, placing it above the water helps keep the water from freezing. On the other hand, how does the water get up through the insulation to the plants? If there are perforations, then the “fastener correction” calc should be done to derate the insulation. This becomes more troublesome the thicker the insulation is. Also, water flowing and draining away beneath the insulation will defeat its winter performance. This will happen whenever it rains enough during the heating season, and there should be another derating for that.  

Third thought: I think the idea of these is there is an evaporative cooling benefit in the summer. So it might make sense for a cooling-dominated building in the right kind of climate — e.g. one with warm summers but not too dry summers — so you get free rain water and don’t have to pump water up for irrigation. In terms of both energy savings and heat island mitigation, I think a foam-insulated and cool-membrane roof would compete very well with this concept and would be a lot lighter. If they are thinking of doing a whole roof this way, I would suggest doing a comparison to such a baseline case on both cost and simulated performance by WUFI Pro.

 

The article about green roof modeling mentioned in the WUFI help is here

Energy and Buildings

Volume 145, 15 June 2017, Pages 79-91

Energy and Buildings

A hygrothermal green roof model to simulate moisture and energy performance of building components

D.Zirkelbach S.-R.Mehra K.-P.Sedlbauer H.-M.Künzel  B.Stöckla

Phius Ventilator Certification Program: An Upcoming Comprehensive Evaluation Tool

The main goal of the Phius Ventilator Certification Program is to comprehensively evaluate heat-recovery and energy-recovery ventilators’ suitability for passive building applications.

Ventilator BlogDefining the end goal of the program was easy, but the path to it has not been. Our technical staff has been busy analyzing existing data, creating a new set of criteria, and tinkering to balance the stringency of the program with available test methods. The end result will be a comprehensive certification program that pairs useful performance data for energy modeling with Phius-specific endorsements for most types of ventilators.

The foundation of the Phius Ventilator Certification Program is the six categories for which it gives out endorsements: 

  • Thermal Performance & Climate Zone Endorsements
  • Electrical Performance
  • Air Quality
  • Defrost & Condensate 
  • Summer Bypass Mode 
  • Acoustics

Of those, only acoustics has non-critical endorsements, meaning that a product can miss out on certification if it does not meet minimum criteria in all these areas — except for acoustics.

The presence of those critical endorsements means it is a certification program and not “just” a rating system. But this program’s evaluation goes beyond a simple yes-or-no certification. Products can earn a variety of endorsements under each of the six categories mentioned above, including climate zone-specific endorsements. 

Another aspect of the Phius Ventilator Certification Program intended to ensure reliable data is its annual verification process. Units selected at random will be subjected to physical testing as a means of verifying that performance remains consistent. In order to make the program as fair and equitable as possible, Phius has developed its own methodology for selecting units for verification each year. The formula is such that products made by “high-volume” manufacturers will be selected more often than those made by “low-volume” manufacturers. 

Building a program of this scope has come with its challenges, but the technical team at Phius has remained committed to making the program comprehensive. This has meant figuring out ways to account for a wide variety of ventilator systems varying from small packaged units to large commercial components. As an all-encompassing program, the Phius Ventilator Certification Program will adapt as new ventilation devices are developed.

As with all Phius product certification programs, the ventilator program aims to collect performance data that can be used for energy modeling while also providing a comprehensive and consistent set of performance standards that can be used to compare products.

As Phius continues to bring passive building into the mainstream, we will continue to provide any and every tool possible to those willing to help. The Phius Ventilator Certification Program is one of the main product-related tools we are providing. We look forward to seeing its impact on the growth of passive building across the world.

Certified Passive House Consultant Training in the North American Context: Then, Now, and Moving forward

The mark of a CPHC...

In May 2008, PHIUS launched the first English-language passive house training program, and with it, the Certified Passive House Consultant (CPHCsm) accreditation.

By the start of 2012, nearly 700 professionals had completed or were enrolled in the PHIUS training program. More than 300 trainees from across the nation had passed the exam to become accredited as a CPHC. And they’ve been busy – they’ve submitted more than 150 projects — residential, commercial and retrofits– for verification in the PHIUS+ Quality Assurance program.

From the beginning, PHIUS classes had a North American accent that was based on real-world

Louisville Courier-Journal article from 1982 detailing a house built in Urbana that utilized superinsulation, airtight envelope, energy recover ventilation, and solar gains. Yes, 1982.

experience.  In 2008, that experience was largely my own and that of a handful pioneering souls, including many who had pioneered passive house principles like superinsulation in the United States and in Canada decades ago.

That’s changed, thanks to lots of committed individuals. Leading these trainings has been a revelation — and an inspiration — for me and my fellow instructors. Our classes are filled with enthusiastic, extremely bright and energetic architects, engineers, builders, energy raters and consultants. Everyone gets – and gets excited by — the fundamental passive house principles. Everyone brings their real-world experience from their regions.  And everyone contributes to advancing passive house.

The result: A continually evolving training curriculum that draws on years of experience and data from a growing community with local expertise.

For example: We’ve learned that hygrothermal modeling – maybe unnecessary in some climates – is critical to successful passive house design in many North American regions. It’s the only way to anticipate and address moisture issues in envelope components associated with humidity that are widely present in the United States and Canada. As a result, students now get a hands-on introduction to hygrothermal modeling using WUFI modeling software. (A free version of WUFI is offered by Oak Ridge National Laboratory and Fraunhofer Institute.)

Similarly, THERM (free download from Lawrence Berkeley Laboratory) is useful to calculate thermal bridging, and students now receive an introduction to using that software tool. Because WUFI and THERM have become de rigeur in many scenarios, we’ve also developed workshops devoted entirely to those tools.

Click on the image to download the PHIUS Technical Committee's paper on evaluating windows for passive house.

The field is developing quickly, and the curriculum will develop accordingly. The existing community of CPHCs continues to build and certify projects and their experience flows back into CPHC classes. The PHIUS Technical Committee, comprising leading passive house practitioners, regularly publishes papers – the latest on evaluating window performance for passive house projects. This year, PHIUS will publish the PHIUS library, a training companion folder that will be updated on and ongoing basis as sections are revised or added (Passive House Alliance members benefit from receiving the newest updates as part of their membership benefit packet for free!).

As our curriculum has evolved, so has the examination process: A computer-based exam component focuses exclusively on North American climates, detailing, construction technology, building conventions, climate-appropriate mechanical equipment and code requirements. Americans can work in Inch Pound units and Canadians can choose metric. Examinees then take home a basic design exercise. This year, for the first time students can opt to take the exam on the afternoon of the last day of class. If students don’t feel ready, they can opt to take the exam at the end of any class program at any location at a later time. The Passive House Alliance US (PHAUS) is also hosting two exams per year in various chapter locations scheduled independently from trainings.

European training providers also offer Certified Passivhaus Designer (CEPH) training in the North American market – CEPH standing for Certified European Passive House. For those who take the European training or have achieved the European accreditation, PHIUS will soon offer an abbreviated training and exam sequence to receive PHIUS CPHC accreditation and listing on the PHIUS Web site.

Join us!

PHIUS has an incredible roster of instructors from around the country. But the buzz in the CPHC training classrooms comes as much from our students as us. (If you want to hear from someone who took the class, check out Jesse Thompson’s account of taking the class on the Green Architects’ Lounge podcast.)

We’ve come this far as a community, and we need to grow the community of qualified passive house professionals if we’re going to achieve the goal of making passive house mainstream. There are more opportunities than ever, as PHAUS chapters begin offering training in their regions, and as partners like Earth Advantage Institute and Carnegie Mellon University begin hosting classes.

Upcoming CPHC trainings include: San Francisco later this month; Salt Lake City in May; June brings New York, Atlanta (in partnership with the local PHA-US chapter) and Portland (through our new partner, Earth Advantage Institute). Seattle training dates, also offered by Earth Advantage, will be announced soon. Boston dates are also in the works.

Check the schedule for updates at the PHIUS site or at the PHAUS National Events calendar.

If none of the sites/dates work, subscribe to the PHIUS newsletter to get updates on additional training sites and updates.

And you can read a full course description here.

See you soon I hope!