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

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.

PHIUS+ 2021 Source Energy Factor for Grid Electricity

PHIUS+ 2021 will include a change to the source energy calculation for grid electricity to more accurately reflect future grid conditions and better weigh the impact of electricity versus natural gas use on site.

In past versions of PHIUS+, the source energy factor for grid electricity was defined by the Energy Star Portfolio Manager and was determined based on past generation and consumption data from the EIA. The calculation methodology accounts for the total primary fuel needed to deliver heat and electricity to the site, including conversion losses at the plant as well as transmission and distribution losses incurred to deliver electricity to the building. Under PHIUS+ 2018, the source energy factor for grid electricity for the U.S. was 2.80, which was an average of the EIA reported data from 2012-2016.

With the release of  PHIUS+ 2021 the calculated factor for the United States grid electricity is 1.73 which reflects a 2050 outlook. 

Figure 1: U.S. power sector evolution over time for the NREL Mid-case scenario

Figure 1: U.S. power sector evolution over time for the NREL Mid-case scenario

Calculating a future source energy factor for the United States electric grid electricity required the combination of three data sets: 

(1) The projected future electricity generation mix, which was taken from NREL’s Mid-Case Scenario for 2050.

(2) Fuel conversion energy factors per generation type from the EIA.

(3) Total system losses from transmission, distribution and storage, taken from eGRID2018 and NREL’s future grid mix scenario.

A detailed description of the calculation methodology and corresponding data sources can be found in the PHIUS Tech Corner article. Read the full article here.