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

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

On International Climate-Specific Passive Projects

Andres-vert3Phius Certification Team Member Andres Pinzon, PhD, explores the process of passive projects being built outside of the United States.

“Qué es una casa pasiva?” reads the cover of the drawing set of the Merlot House, a project submitted by CPHC Ignacio López pursuing PHIUS+ 2018 certification in Baja California-Mexico. This project — the first in this country — adds to the growing interest of Phius certification across latitudes.

During a regular week at Phius, we move between reviews on different climate zones, building functions and building types, assessing data from residential and non-residential, new construction, or retrofit. 

At first sight, the path toward certification may look intimidating, and we at Phius know that. Our team offers guidance and support for project submitters, especially when working on their first projects (overseas or not). The reviewers go above and beyond in helping project teams meet the specific, wide-ranged, and performance-driven goals of their buildings. This process offers achievable steps for certification within the context of each project.

How does Phius do it? The process includes: rounds of review, real-time feedback, conference calls, online open resources, etc. Phius tailors this process by providing solutions in compliance with certification, looking for red flags, and pointing out paths to avoid. This allows us to work with clients, architects, engineers, building scientists, etc. on the critical aspects of certifying a project in a particular part of the world.

Here are some remarks from our experience working with projects submitted to Phius outside of the mainstream of US and Canada.

The first step is generally custom climate data, followed by calculating the project-specific performance targets. Using the appropriate climate data and performance targets are essential to accurately modeling and reducing energy loads. Phius generates custom climate datasets for project teams that accurately represent their current project’s location. For most locations, we have not had trouble finding a TMY3 station within a (80-km) 50-mile range.  

In addition to climate data, marginal costs of electricity ($/kWh) at the regional/national level are needed to calculate the custom space conditioning targets they will use for certification. With this, teams can begin to work on comprehensive design and energy modeling; aware of the demands and loads that are expected for their buildings. 

Phius has projects in places such as Japan, Colombia, Nigeria and Mexico, where Phius certification represents a third-party verification on a desired performance for energy use and high-quality housing (see post on Housing Equity). The accumulated experience of different situations helps Phius come up with new solutions for diverse challenges and pass that knowledge to teams in subsequent projects.  

For example, approaches on cooling and dehumidification seen in Phius projects in southern states can guide us on how to tackle larger demands and peak loads in projects in tropical areas of South America or Africa. We see this potential in aspects such as: the enclosure’s insulation and airtightness, shading dimensioning and optimization to avoid overheating, and the proper selection and sizing of mechanical devices.  

Energy and carbon saving targets in buildings and operational budgets are a global concern. However, some information might be lost in translation when moving between countries, languages, cultures, or systems of measurement. In this sense, Phius is working on expanding the limits on a technical language that might hinder the domain of Phius projects.

Phius’ CPHC training is also offered and taught in SI units. In this way, professionals abroad who are interested in earning this credential can have access to material on building science principles, design exercises, and software tutorials prepared in the metric system. Furthermore, WUFI® Passive, the energy modeling software used for Phius certification, allows users to easily toggle between SI and IP units any time during the process.

More actions are in development within the idea of expanding the Phius community abroad. It is exciting to see creative and innovative approaches, integrating different sorts of information to make a high-performance building, such as the “bilingual” drawing set from the Merlot house. I cannot wait to attend the breakout session on international climate-specific passive projects at PhiusCon 2021 to continue the conversation.

Early morning decarb musings…from the bottom up…join the conversation!

Note: After contributions from a number of fantastic guest bloggers, Katrin Klingenberg makes her return to the Klingenblog to give readers an inside look at her quest to achieve carbon neutrality both in her own life, as well as with her work at Phius.

It is June of 2021. Sipping my morning tea, reflecting. It has been a year of thought and reassessment and remembrance, letting go of the old ways…quiet before the storm…I feel grateful almost …the pandemic was harsh…training wheels for what is to come…are we ready?

In interviews with journalists, I often get asked: what was/is your core motivation? Why did you start Phius?

And my response is always along these lines: “I was looking for carbon neutrality in all aspects of my life; to take personal responsibility in light of a crisis, wanting to do my share, love and respect for the commons, a desire to distribute resources fairly so that all people can live in peace, balance and harmony.”

And then, as an architect, I recognized that buildings represent a big chunk of our global carbon emissions. Phius was my chance to be part of the solution. My professional commitment since 2002: I could no longer continue to add to the planetary carbon bill with my work. That effectively meant setting up every building to be capable of achieving zero and positive energy.

Climate change is an existential crisis that no one will be able to talk their way out of. There are no planet hospitals with a line out the door that impress on us how bad this is, no healthcare providers ringing the alarm. Well, actually…scientists and environmentalists have been sounding the alarm since the 60s. Society stuck its head in the sand and decided on doing fossil fuel biz as usual as if there was no tomorrow (pun intended). Consequently, we are really up against the wall now. We need courageous, superhuman really, political will and global consensus, turning every conventional notion of how things used to work upside down. We need a fast and effective campaign to inoculate our economies against the effects of shifting away from fossil fuels as fast as possible, just as fast and successful as the COVID-19 vaccination campaign.

The good news: Carbon neutrality is within reach. We are so close. That was our goal on our inaugural website in the mid 2000s. The Passive House Institute US declared its mission: making passive building standards code by 2020. 

For all intents and purposes, check! We effectively have achieved that goal in places that matter a lot, not as mandatory code but in the form of programs, incentives, local laws, alternative compliance paths: New York City, the State of Massachusetts, Washington State, Washington DC. And we initiated ASHRAE 227p. So, yes, on our way, check!!!!

And in its 2021 standards update, Phius made a very important decision – the flagship certification, while the zero energy passive baseline still exists – is now the Phius ZERO certification. I am so proud of our team, how far we have come as a community and how patiently we have built this shift together over the last 20 years. It is a marathon, not a sprint — sound familiar?

But we need to pick up the pace. Turning the entire building industry around is only step one. Even if we eventually build all new construction to our proven standards, decarbonize all buildings through deep retrofits, and decarbonize the energy supply, we still urgently need everybody’s help from the bottom up to take action.

That’s really what I’d like to discuss here. Start a discussion about meaningful personal action that can be taken by anyone who chooses to go in on this really important mission.

I’ll go first. Since all this has been a driving force in my entire life really, it has shaped my life path and my choices. Carbon neutrality requires rethinking and changing a few things.

In 2002, I decided that if I truly believed in the commons and fair share of resource distribution for everyone, I would have to walk the walk. 

I tried to determine the standard of living that could be attained by everyone in an equitable society while also meeting the carbon reduction goals required to adapt to and mitigate climate change. That meant reassessing everything in my life: where do my actions and life contribute to the problem and how can I fix it? Once you start thinking about it in this way it really ripples through everything. 

Let’s start with money. We all need to earn money to run our lives. Our economies run on oil. Every dollar in our pocket essentially represents wealth generated in some form by fossil fuels. The more dollars any one of us has, the more emissions you are essentially responsible for in your daily life transactions (carbon footprint by wealth category is another interesting topic, another blog). I decided to limit the money I was going to earn. And I decided to put the money I did earn back into the non-profit Phius to support market transformation toward zero energy buildings. 

I then, step by step, dialed in my living circumstances: how much space I was able to live in to stay within my fair-share space conditioning emissions budget, how much land around my house there should be and how I was going to use it (farming), my choice of car, vacation and travel miles, food choices…all had to be reassessed.

It was a process. But I’m happy to report that in 2021, reflecting over morning tea, I feel good. I feel really, really good about having achieved what I set out to do…at least in my personal life.

Smith House

Smith House

With little money to my name and no job at the time, I embarked in 2002 on building the Smith House like there was going to be no tomorrow if I did not do it. It was scary, but it turns out, where there is a will there is a way. 

The Smith House, 1000 sq ft, meant for three people, was built for being zero energy ready. In 2018, I finally added a 5 kW PV system, taking the house and about 10K electric car miles per year (a car which I don’t have yet) off the planetary carbon bill. 

What I overproduce in Urbana “pays” for my condo living in the city (since I am not using overproduction to drive). I never turn my heat or air conditioning on. It’s a small, but nice and comfy apartment, 30 minutes walking distance from everywhere I need to go. I have not been on planes, trains and automobiles in a long time and if I do get on I am conscious of each mile. 

I changed my diet, essentially vegan plus fish and an occasional egg. Looking at carbon emissions savings from those food choices…turns out they are very significant. I try to avoid the elevator, though, full disclosure, my apartment and office are both on the 14th floor, so that’s a challenge. Down is easier than up, let’s start there.

And…I’d like to deep energy retrofit my condo tower…already have a plan…but that for the time being will have to be done in the future.

What are your stories?

If you are interested in making similar changes, 2000-Watt Society is a great place to start.

Step it up from Earth Day to Energy Independence Week

Here’s a great idea from Graham Wright, PHIUS Senior Scientist and Chair of the PHIUS Technical Committee. We hope you’ll take up the challenge.

So, Earth Day was great, and everything. And the Earth Hour there.

Energy Independence Week. It's fun, it's patriotic, and we're virtually certain Stephen Colbert would approve.

Energy Independence Week. It’s fun, it’s patriotic, and we’re virtually certain Stephen Colbert would approve.

But let’s be real, Earth Day doesn’t challenge you to actually do anything in particular, and while Earth Hour does, that is vanishingly little  — one hour out of 8760 is addressing like 0.01% of the problem. After how many years now of Earth Day, what do you say we step the game up?

I call it Energy Independence Week. The idea is that, you extend the 4th of July holiday to a full week, during which you observe these three rules:

1. Use no grid electricity.
2. Burn no fossil fuels.
3. Make no trips to the grocery store.

It’s patriotic and fun. Like a staycation. You’ve got the charcoal grill out anyway. Notice that it’s twice as good even as “1% for the planet” in a couple of ways.

A) it’s 1 out of 52 instead of 1 out of 100, and
B) it’s not just a sacrifice concentrated on you for a diffuse benefit to the planet – it increases your own resilience.

I did this in 2008, a few months before I ever heard of passive house. But I like how it ties in – because of the time of year, it focuses attention on avoiding overheating, not a bad thing. (You will be fine if your passive house is not designed too hot. 😉 And it’s forgiving to the many of us who do not yet live in passive houses; this would be a much harder challenge yet in the winter, in most places.

At the time, I was living in rural Minnesota in a straw bale cottage, so heating and cooling wasn’t a problem. I got by with one solar panel and one battery for electricity. That was enough to run the well pump and my laptop. You don’t need much lighting in Minnesota that time of year. Instead of hot showers I swam in the river, which was a short bike ride away. It’s like camping but, you’ve got all your books or shoes with you.

Your challenges may vary. On rule 3 there, stocking up ahead of time is ok, preparations are part of the idea here. One of the other preparations I made was for irrigation — at the time I was trying to keep a bunch of discount hazelnut seedlings alive in the baking sun. I figured my little panel could not generate enough electricity to run the well pump for that, so I set up a big water barrel so I could gravity feed the orchard. Yeah, I faked it by filling it from the well ahead of time; ideally it would have been a real rain barrel all along.

Again, learning stuff like this is part of the fun. So, I hope you’ll take up the challenge and start planning now. And please, share your strategies, tactics, and experiences in the comments section here at the Klingenblog.