FAQs: The Importance of Commissioning a Zehnder HRV or ERV System

In the excitement of finishing a construction project or moving into a new home, it can be easy to overlook the final step in correctly installing an HRV system: commissioning. Our latest blog article explains why Zehnder units need to be commissioned and what happens during the process.

Why do Zehnder Units Need to Be Commissioned?

All ventilation systems need to be commissioned, especially those that have HRVs and ERVs.  With a Zehnder unit, commissioning and balancing is the way to get the most out of the equipment. 

During the commissioning the flows are measured in each room.

During the commissioning the flows are measured in each room.

When a system is initially installed, it’s probably pretty far out of balance. The Zehnder system is both simple and complex: ducts run from the outside of the building to the HRV, and then from the HRV; more ducts are run to the bedroom, living room, bathrooms, and kitchen. All houses are different shapes, so the length of the ducts and how much they twist and turn through the house varies from house to house. These differences impact the supply and exhaust flows by adding different levels of resistance pressure between the supply and return ducts. The resulting pressure loss makes it harder for some ducts to carry air than others. The Zehnder system has two fans which turn at the same rate, but because of the difference in pressure loss, the result is two different rates of flow running across the core, putting the system out of balance. 

What happens in commissioning?

Basically, commissioning is the process of balancing the flows for incoming and outgoing air in the heat or the enthalpy recovery core. When the two flows move across the core at the same rate, the system operates at peak efficiency for both heat and/or enthalpy recovery. 

In commissioning, both the supply and return flows are measured to find out how much they are out of balance. Once measured, they are then corrected by adjusting the fan speeds up or down to put them in balance. After this is done, normal fan speed settings for the home is set as well as the rate for the low occupancy rate, and the boost rate. 

What is the boost rate?

The boost rate is basically kicking the HRV or ERV unit into high gear, after a shower to pull the excess moisture out of the bathroom or to pull excess cooking smells or exhaust out of the kitchen. It’s just running the fan on high speed for a pre-determined amount of time, which could be 15 minutes or 45 minutes. The boost time is whatever time the occupants want to set their boost rate to run. It’s a decision that’s made early on in commissioning and once it’s selected, the system goes into boost for the selected amount of time every time the boost button is pressed.

Besides checking and adjusting air flows, what else happens in a commissioning?

In addition to balancing the airflow, especially with Zehnder systems, some other important steps happen in commissioning. One of the biggest is confirming and setting the fireplace program.

When a home has a fireplace or some other combustion device, it’s possible in colder climates, and overnight lows in some conditions, that the system can turn into more of an exhaust fan than a ventilation system. It does that to keep the core warm because it’s really quite cold (below freezing) outside. When this happens and there’s a fireplace, there is the risk of pulling wood smoke or other combustion gasses out of that combustion area and into the home, which can be uncomfortable or even dangerous. So one step of commissioning is to confirm the presence of combustion gasses. If so, we set a program to make sure there is adequate preheating; that way the system can’t go into imbalance and will operate in the cold temperatures in the project’s location.  

Additionally, at commissioning, the commissioning agent will confirm that the system was installed as designed and is working right. The agent will also check that all filters are new and clean and that any other special applications (such as a ground loop defrost or other optional accessories) are there and are working correctly.

How important is commissioning?

Commissioning is really important for the functioning of the system. Without final commissioning the system is undoubtedly operating out-of-balance and the room to room flows are not going to be operate within the parameters of the system design. It’s vitally important that commissioning be completed so the system can do what it’s intended to do.

When in the building process does the commissioning happen?

Commissioning happen at the end of the project, just before occupancy of the building or just after occupancy. Some building codes require it prior to issuing an occupancy permit.   

It’s best to commission just at the point where everything has been installed and is running right. The building should be cleaned up a little bit, so we’re not sucking in drywall dust and construction debris, and all the grills and diffusers should be installed.

How long does a commissioning take?

A typical commissioning for a 2,500 square foot home with three baths and three bedrooms can take three hours or more to complete. 

Why is it recommended that someone other than the person who installed my Zehnder be selected to do the commissioning?

Small Planet Supply prefers to work with third party commissioning agents. Typically, installers can run into some challenges installing the system and they can make choices that don’t lead to the system running as well as it could. A third-party commissioning agent is more likely to identify these issues since they are a set of fresh eyes and can compare the job to the system design and then balance it as recommended. 

Commissioning is really the homeowner’s final assurance that the installation is done correctly and that the system is balanced. On occasion we can have the same installer do the final commissioning. We don’t see that happening often and when it does we’re typically working with an installer that we know quite well and that we have high confidence in their work. 

Who arranges for commissioning?
 There are a number of people who can arrange for commissioning. It can be the HRV system installer, the project’s general contractor, or it can be the homeowner who wants to get their system balanced and commissioned. The process starts with filling out some questions on the Zehnder America website which triggers a chain of events. One of the chain of events is that the system plan is returned to the system engineer where it receives a final review. A copy of the plans is sent to Small Planet and then a commissioning agent is assigned to it.

The commissioning report details final air flow measurements and other information that assures the system has been installed correctly and has been adjusted for optimal comfort and efficiency.

The commissioning report details final air flow measurements and other information that assures the system has been installed correctly and has been adjusted for optimal comfort and efficiency.

How can commissioning be completed most easily and without extra cost and frustration?

Make sure that all the work is done before a commissioning agent comes to commission the system. One common frustrating situation is when the agent comes before the system is ready. The commissioning agent is not there to finish installing the system. The system needs to be up and running, with all controls, terminations and diffusers in place and functional before the agent arrives to commission the system. One of the pre-commissioning steps is a dialogue with someone on the project to make sure the system is ready, because if it’s not ready then the commissioning agent has to come out again, which triggers another charge.  

How does a homeowner know that their commissioning has been done, or been done correctly?

At the end of a commissioning, we supply a commissioning report to the homeowner and the installer.

What if you’re unsure whether your home/project Zehnder unit has been commissioned?

Commissioning reports for Zehnder systems sold by Small Planet Supply are retained on file at our company and are available to the homeowner. Small Planet Supply just needs to know the address of the project and when it was installed.  

If it has been a long time since a system’s been commissioned, another option to consider consider is to have the system looked over and commissioned again. This often makes sense after a remodel, a major event, or to just have the system inspected and rebalanced every three to five years.


ThermaCork: Seven Reasons Why We Love This Durable, Sustainable Building Material

Small Planet Supply has been importing and selling ThermaCork expanded cork since 2012. While we’ve been sold on the outstanding qualities of cork for years, we may not have been as great at communicating to others why we think it is one of the best building materials on the market today. So, in honor of seven years of ThermaCork, we’re going to share seven reasons why we love ThermaCork.

Reason #1: ThermaCork is 100% Natural

Expanded Cork being made in Portugal - Just two Ingredients - Cork and Steam

Expanded Cork being made in Portugal - Just two Ingredients - Cork and Steam

ThermaCork has two ingredients: cork and water (steam). ThermaCork is made from cork granules which are steam-heated, causing it to expand. Steaming also activates suberin (a natural binder) which causes the cork granules to stick together creating the solid cork blocks. You can see more at the Manufacturing page of ThermaCork’s website.

Reason #2: Cork is a Carbon Negative Building Material

Cork trees sink and sequester carbon as they grow. There is a pretty cool video explanation about how ThermaCork calculates its carbon-negative status at ThermaCork’s, “Why Use ThermaCork” page.

Reason #3: ThermaCork is Sustainable

Cork is harvested from the cork oak tree every nine years. Skilled cork harvesters split off the bark of the tree without damaging the rest of the tree. In fact, cork tree harvesting actually improves the tree’s health and vigor.

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Reason #4: ThermaCork Has Multiple Products for Multiple Applications

ThermaCork has four types of products that are useful to the design/building community:

  • ThermaCork Insulation Cork

  • Thermacork Facade Insulation Cork(exterior insulation which also serves as the building facade)

  • ThermaCork Decorative Cork

  • ThermaCork High-Density Anti-Vibration Cork (prevents the spread of vibration over a given surface to be transmitted to the contiguous space)

Reason #5: Cork Has Been Used to Insulate Throughout History

The ancient Romans used to put cork in their shoes to keep their feet warm, and to insulate their roofs. In the Middle Ages, monks in Spain and Portugal sheathed the inner side of the walls in their monasteries with cork. In the USA, cork was used as insulation in ice houses, ice and cold storage plants, household refrigerators, and even houses themselves (as you can see in the advertisements to the right).

Reason #6: ThermaCork Can Be Used for So Many Things

While we knew that there were a lot of uses for ThermaCork for building interiors and exteriors, we were pleasantly surprised by the other uses people came up with for our product:

Reason #7: It’s Just So Darn Beautiful

We fell in love with ThermaCork’s simplicity, warmth and beauty. The slide-show below has some of our favorite projects and there are some resources below for you to continue your own exploration of cork.

Resources to learn more about expanded cork

More about ThermaCork:
Thermacork website
Small Planet Supply
Amorim (Cork Manufacturer)

More about uses of cork in the early 20th century:
Book on Cork Insulation from the North Eastern University Library.

Recent Articles Featuring Cork:
”Wine Be Damned, Cork Is For Building”, Journal of the American Institute of Architects.
"The Perfect House for a Bouyant Market! Home made from cork, a council estate and an opera theatre are in the running to be UK's best new building. Daily Mail - 7/18/19
"Durable, Adaptable Cork", NY Times - 4/26/2019


Albert Rooks and BILL Hayward Share more than the same taste in jackets - they are both committed to helping builders and homeowners create healthy, energy-efficient buildings.

Albert Rooks and BILL Hayward Share more than the same taste in jackets - they are both committed to helping builders and homeowners create healthy, energy-efficient buildings.

Small Planet Supply’s CEO Albert Rooks and Hayward Healthy Home’s (H3) CEO Bill Hayward are excited to announce that they have merged operations.  The merged company will operate under the name of Small Planet Supply USA under the direction of current CEO Albert Rooks. 

Merger’s Positive Impact

This merger is an exciting development for both companies, as well as for builders and consumers.  Small Planet Supply has been supporting the growing energy-efficient building market since 2010, offering building materials and education in the Pacific Northwest and Western Canada. H3 has been providing healthy home systems to homeowners and builders in California and Southwestern states since 2014.

Hayward, who is also CEO of Hayward Lumber and founder of Hayward Score, is excited about the impact the expanded company will have. “This merger will allow us to provide a full complement of services to both homeowners and builders,” Bill Hayward said.  “When we looked at the mission of each company, we realized quickly that we both provide products that help support healthy homes and a healthy planet.  We’re looking forward to providing even more products and services to our customers in the future.”

The partnership is already yielding results.  Small Planet Supply has been selected as a technology vendor at Sonoma Clean Power’s Advanced Energy Center, which will open in October 2019.  A new Small Planet Supply warehouse location in California is being considered.  Small Planet Supply’s CEO Albert Rooks is excited about the possibility.  “Small Planet Supply expanded to British Columbia just as it was implementing its new energy standards.  We’ve been working with the province, builders, and homeowners to help them meet the new building requirements. We’re excited to have a larger presence in California as they begin adopting their new code.  Our company’s focus on healthy, energy-efficient materials will assure builders and customers that they are getting both earth-friendly and health-protecting products while meeting the code.”

Small Planet Supply Product Availability

While Small Planet Supply’s physical presence will be in the Western United States and Canada, customers from across the United States and Canada can order products via Small Planet’s online store 24 hours a day.  Customer service is available 8:00 am to 4:30 pm weekdays.  

New KlimaGuard Line Helps Small Planet Supply ‘Stick’ to Its Values

“ Our climate crisis necessitates that all builders need to have access to these materials if we are going to meet our climate goals.”

Our climate crisis necessitates that all builders need to have access to these materials if we are going to meet our climate goals.”

Starting in April, Small Planet began offering a new line of high-performance building tapes called KlimaGuard.  Since we already offer a number of high-performance tapes, you may be wondering why we’ve added another line to our inventory.  The answer is quite simple: incredible value.   Small Planet Supply CEO Albert Rooks made this change to address an unmet demand in the market.  “Builders want to construct better buildings,” Rooks said, “But the high cost of high-performance tapes makes it difficult to stay within budget.”

Rooks researched European high-performance brands and worked with a well-known manufacturer to develop a tape that is both high-performing and high value.  You may be wondering, why is this being released now?  “It’s a matter of urgency,” Rooks said.  “Passive House builders have known for years the contribution high-performance tapes and membranes make to creating an airtight-envelope.  Our climate crisis necessitates that all builders need to have access to these materials if we are going to meet our climate goals.” 

Check out the first products in our high quality, value-priced line.

Check out the first products in our high quality, value-priced line.

“These tapes are our first step in providing affordable building envelope products”, Rooks elaborated.  “We’ve started with three simple applications: Exterior sheathing and membrane joint sealing with a two-inch tape that’s rated for six-month exposure and sticks to virtually everything. We then took the same tape and made a 4” wide version that sticks to wood and concrete without a primer for joining walls to foundations, going around corners, or into rough openings. The tape in all sizes is not only vapor-open but is also variable like the “smart” membranes.  Finally, we took the same “crazy-sticky” acrylic adhesive tape and made a version for windows. It has a unique printed line at 5/8” on one edge and a matching split back for placing on the interior or exterior of the window to rough opening joint. The backing material is fibrous and can be painted or plastered over. This first series of KlimaGuard are made in Germany and the quality is excellent. The motivation behind bringing these new tapes into the market was to drill through the cost barrier and offer high performance tapes at ‘building code’ like prices. “

Wondering what’s next on the horizon?  “We have more ideas in development!” Rooks noted.  “On the books for introduction at Small Planet Supply in the next twelve months is a new interior membrane, new interior tapes, and more hydronic fan coils.  We will also be working more on our company’s internal processes so we can make asking questions, discussions, and ordering easier for everyone.  The end goal is to help more homeowners and builders purchase and confidently install quality, high-performance products in their buildings.”

In the meantime, our first three tapes are available at these low introductory prices through September:  Two-inch sheathing and membrane tape is $19.90 a roll, three-inch window tape is $29.74 a roll, and four-inch base and corner tape is $38.12 a roll.  Learn more about the tape on the KlimaGuard page of our Small Planet Supply website.  To order now, click here.


New Zehnder Q and ComfoPost Arrive Right on Cue for New West Vancouver Passive House

Albert Rooks and Shawn Barr collect final numbers for the Zehnder commissioning.

Albert Rooks and Shawn Barr collect final numbers for the Zehnder commissioning.

Last Tuesday, Small Planet Supply’s Albert Rooks met with Shawn Barr of Naikoon Construction to complete the final commissioning of the first Zehnder ComfoAir Q and ComfoPost in North America at the Radcliffe Passive House in West Vancouver.

The installation of the new Q system wasn’t an accident. Radcliffe Passive House owner James Dean was aware that the Q would soon be released in North America and wanted it installed in his new home since it represents a whole new level of heat recovery ventilation. 

Dean is also no stranger to this technology, as the ERV enthalpy exchanger and membrane comes from CORE Energy Recover comes from Core Energy Recovery Solutions, a company he founded.

More Sophisticated Technology Makes System Balancing Easier

New Zehnder Q

New Zehnder Q

Albert Rooks expressed excitement about the new unit because of the sophisticated operation of the unit which made installation easier. “It was really exciting because the unit measured the static pressure of the ducting system for the entire house and then confirmed the maximum airflow possible through the ducting, after which it self-balanced the supply and exhaust flows. This allowed me to input my target design flows without having to measure. From there, it prompted me to balance the room to room flows from within the home as the final step in the system’s commissioning wizard.”

This is an improvement from previous Zehnder products. In prior models, all of the balancing had to be done by hand, in a trial and manner fashion. The new version is much easier to commission, especially for remote locations. Another new feature also helps with remote locations. When the Q system is internet enabled, it makes it possible to remotely diagnose system problems.

First ComfoPost in North America Conditions Air

Zehnder ComfoPost, installed.

Zehnder ComfoPost, installed.

As briefly mentioned previously, the Radcliffe Passive House design didn’t just stop with the Zehnder Q, this system is also equipped with the Zehnder ComfoPost. The system takes heating or cooling from water brought into the home via a heat pump, putting it into the ventilated air. This reduces the amount of refrigerant needed which is better for the environment, while allowing occupants to use the Zehnder system to change the temperature in their home. Dean selected a Daikin heat pump that also produces domestic hot water.

Why did Dean decide to use the ComfoPost in his home? "Once I saw how little heating and cooling we needed from having such a well-insulated and airtight building envelope, I realized that we could really simplify the HVAC system by integrating the heating and cooling with the fresh air ventilation system. We considered using in-floor radiant, but decided it wouldn't feel comfortable when cooling and would rarely be used for heating and we wouldn't feel the warm comfort of the floor because the temperature differential of the floor and air is so small," James Dean noted. "The air quality, temperature and humidity levels from the Zehnder ComfoAir ERV and the ComfoPost is perfect."

Since ComfoPost is new to North America, Albert Rooks has applied to BC housing for a grant to support data collection of the ComfoPost unit. The study would help determine how effective the temperature transfer is on the low-flow ventilation air. The hope to find that due to the coil’s design that the transfer efficiency is quite high since its sized for low air flow and high transfer efficiency.

Custom Grills Made for Trickier Installation

The custom made grills caused problems with the commissioning. Sealing them and putting them back in placed fixed the problem.

The custom made grills caused problems with the commissioning. Sealing them and putting them back in placed fixed the problem.

Without a doubt, the decision to make custom grills for the passive house added to the clean lines that the house enjoys. However, the wood grills weren’t sealed tightly to the distribution box causing air to leak, throwing off the readings. This was remedied by removing the grills, getting everything sealed and then putting them back in place.

After one last measurement of the system with the air flow meter in both normal and boost mode, Albert completed the commissioning paperwork, verifying that West Vancouver’s passive house is not only beautiful, but balanced too. 


Using a Change Model to Better Gauge Customer Readiness for Change

If you’re an architect or a high-performance builder, you may not think that you have much in common with behavioral health professionals, but in certain cases you’re doing the same work that we do: getting people to change their behavior.  If you’re one of the lucky architect/builders who only gets clients who are 100% motivated to build energy-efficient homes, this isn’t the article for you.  If you find yourself frustrated and unsure why a client who seemed really motivated just disappeared, this article might be worth a read.

Therapists have long wrestled with what needs to happen to get individuals to intentionally change their behavior.   One theory, The Trans-theoretical (TTM) Model of Change (Proschaska & DiClemente) purports that people move through five (or six) stages when they change.  For therapists, behaviors  we’re dealing with are are things like quitting drinking or smoking, losing weight, etc.   While it may seem “obvious” to therapists why doing these things are positive, the key to helping clients achieve their goal is to understand where a client is in the process to match our strategies with where they are in the process.

For those who have “drunk the Kool-Aid” of high-performance building, it seems natural that everyone should get why high-performance homes are (obviously) the best choice (goal). It can be hard to remember that there was a time when we didn’t know why it was better to have tight envelopes, vapor-permeable barriers and fuel-efficient mechanicals.   Being able to identify where customers (and potential customers) are in the change process can help you use strategies specific to a customer’s stage of change and help you avoid unnecessary effort. 

Change Stage 1: Pre-Contemplation (or the  “What”) Stage Customers:

This is the stage of customer you may not see come through your doors, or may see by accident.  A friend told them about this architect who “built this beautiful home” but the desire to build an energy-efficient home isn’t there.   They may be hoping that you will build them the McMansion of their dreams. 

Strategies for Stage 1 Customers: Validate the desire to own something beautiful while encouraging the customer to consider how building a more energy-efficient home could be healthier for their family and the world.  In this stage you are just “planting the seed” that there can actually be a different way to build (or retrofit) a home.

Change Stage 2: Contemplation (or the “Why) Stage Customers:

This is the stage where most new customers come in.  They think they might like to build a healthier, more efficient home but they’re not sure they want to do it or how to build a healthier home if they want one. 

Strategies for Stage 2 Customers:

Validate that this is a big step and that the choice is theirs.  Encourage them to identify what the pros and cons of building a higher-efficiency home.   Listen carefully to the reasons they give so you can better understand their motivation. Help them identify positive things that will occur in their life as a result of their building choice. 

Change Stage 3: Preparation (or the “How”) Stage Customers

In this stage, the customer is starting to move toward a commitment to change – they are taking active steps to learn more about the new type of home they will build (or retrofit).

Strategies for Stage 3 Customers:

Encourage them to visit homes that are similar to the one they want to build.  Help them connect to other homeowners who have built highly efficient homes.  Encourage the customer have realistic expectations about the building process and ensure rapport with your customer is good.  The hardest (and best) stage is just ahead.

Stage 4: Action (or the Building) Stage Customers

This is when it happens.  The commitment is made and the house is being built.  With even the best planning, there are bound to be things that happen that can be upsetting: delays, cost increases, etc. 

Strategies for Stage 4 Customers:

When upsetting things occur, it can be helpful to try a two-step strategy.  First, empathize with the customer about the issue (most likely there is a really good reason to be upset) and second, refer back to the reasons the customer identified in Stage 2 about why they wanted to build an energy-efficient home.   By reminding them of the reasons why they made their choice, you are using their own words to remind them of their commitment.

Stage 5: Maintenance

It’s happened!  Your customer has moved into their house.  The pictures are on the wall and the barbecue is on the deck.  Other than making sure the check doesn’t bounce, there are still a couple more things you can do to help your customer in this strange new energy-efficient landscape.

Strategies for Stage 5 Customers:

During the euphoria of “finally moving in”, many customers aren’t focused on the mechanics of their new home.  Make an appointment two to three weeks after move in to go over the mechanical systems and other home features that may be new to the customer.  If there is an HRV or ERV, go over how the system runs, changing filters, etc.  Make sure your customer knows how to use all the equipment in their new home.  Help them identify any stumbling blocks that may make it difficult for them to keep their home performing well.   This will make it easier for them to avoid the sixth stage of change, “Relapse.”

Stage 6: Relapse

Hopefully none of your customers end up here, but it can happen.  Your customer turns off their HRV and can’t figure out why the house “doesn’t seem right” or drills holes in the ceiling to put in some fancy canned lighting, only to ruin your airtight building plan.   

Strategies for Stage 6 Customers

The first thing to do, of course, is to help the customer fix the problem.  Then, have a conversation about what triggered the issue (“I didn’t think I had to have the HRV on all the time” or “No one said I couldn’t make changes to the lighting”) or where misunderstandings may have occurred.  Help the client problem-solve how to avoid the issue in the future.  

There you have it, a little primer about stages of change!   For more information on creating your own change, check out:  “Changing for Good”: by James O. Prochaska and John C. Norcross. 

Have Truck, Will Travel: Reflections on the First Half of our BC Airtightness Workshops

Have Truck, Will Travel:  Reflections on the First Half of our BC Airtightness Workshops

Have Truck, Will Travel:  Reflections on the first half of our BC Airtightness Workshops

It was with a mixture of excitement and fear that Small Planet Supply accepted the contract award to provide mobile airtightness trainings across the BC Province.  The grant was a combined effort of Fortis BC, BC Hydro, the Province of British Columbia and BC Housing.  It wasn’t teaching the classes that seemed intimidating; it was the thought of navigating the sheer size of British Columbia, how to connect with communities across the region and how to replicate the hands-on portion of the BCIT held classes in local trainings.   Since late September, we’ve conducted twelve classes and trained 143 people. Here’s a little of what we’ve learned so far:

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Cork on the Outside of the Bottles

Cork on the Outside of the Bottles

Last Friday, Albert Rooks and I were in Lisbon for our third Amorim Cork Conference. The two-day conference highlights innovations in cork use. Amorim is the world's largest cork producer and manufactures cork flooring, cork stoppers for wine and our own Thermacork.

This year, following a tour of the factory (more on the factory tour soon), we were surprised with a site visit much more fun then last year's school tour - Fitapreta Winery, located outside of Evora.

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