Tag Archives: research

3/8 inch and flowing

“I told you so!” – was coming to my mind while looking at the plumbing in a Swedish single family home built sometime in the 1970’s.

Some plumbing lines were partially exposed to keep them in the interior conditioned space. What caught my eye right away was a 3/8 inch branch (or twig) coming off of a 3/4 inch trunk line.


The use of 3/8 inch plumbing lines (or twigs) fits right with the material and energy conservation goals of an efficient domestic hot water delivery system, as was explained to me by the hot water guru Gary Klein. The problem for us in Chicago is that the smallest allowed pipe diameter per plumbing code is 1/2 inch. The rationale behind this limitation is, so I assume, concerns about pressure drop and insufficient flow capacity. But it also puts a limit on the efficiency of our hot water delivery system.

Seeing that a built 3/8 inch twig line didn’t cause the world to implode was rather exciting. Not only that, but the 3/8 inch cold water line services three fixtures: 1) the toilet, 2) a sink, and 3) a shower, while the ? inch hot water line only serviced the sink and the shower.

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The structured plumbing system that I have described in a previous post, recommends the use of 3/8 inch twigs. But each twig should just service a single plumbing fixture, not multiple fixtures.


Serving three fixtures with cold water and two fixtures with hot water using a 3/8 inch twig lines would take us – so one could argue – into deep water. That begs the question: Why would several fixtures on one twig be acceptable?

The bathroom in the Swedish single family home is meant to be used by a single person at a time. In other words, you shouldn’t need to worry about somebody flushing the toilet or using the sink while you take a shower.

And I used that shower. There was no problem with the water flow rate or the water pressure, despite the nine feet long 3/8 inch twig. And being the nerd I am, I let the shower run while flushing the toilet or turning on the sink faucet. There was a very brief but minor pulse in the shower’s water flow, but other than that, no detectable flow reduction or pressure loss.

For full disclosure, I should mention that the bathroom in question was on the 1st floor and only a few feet away from the water heater and water main. The second floor bathroom has a different set up. Here a 1/2 inch twigs (or branches) services the various plumbing fixtures, probably to mitigate pressure loss that may come with the elevation and friction that comes with the longer pipe run.

Now – is that 3/8 inch twig I observed an exception? Apparently not. I noticed almost the exact same setup in a restaurant men’s room — a 3/8 inch twig servicing all fixtures.

As unscientific and nerdy as this is, I am delighted to see proof that 3/8 inch twigs can work and can be safe. But to whom can I take my “I told you so?”

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Has the cabin fever set in by now? If so, let me lead a quick expedition into the hot and muggy summer months. Even though we may yearn for summer heat at this time of the year, once it is upon us, we are rapidly looking for ways to keep cool. How do you keep cool?

I dislike the typical excessive air conditioning we exercise, but I am a big fan of ceiling fans.

You could argue that any ceiling fan would do a good job as it is most likely to operate more efficiently than a conventional air conditioning system. This comparison is somewhat unfair as the product of air conditioning is different from that of a ceiling fan. But then again, humanity is famous for buying products that are non-essential.

We needed to make a decision about what ceiling fans we should acquire for our deep energy retrofit. I started by looking at the extremes. On one end there is the $25 product, cheap but flimsy, “delightfully” humming along while it moves air (for all those lovers of white noise), and dumping the one thing from the motor and light that we want the least – heat.

On the opposite spectrum is … well, other than expensive, I don’t really know. This is a good time to consult the EnergyStar product list for ceiling fans.


EnergyStar rates the efficiency of ceiling fans by how much air they move (cubic feet per minute or cfm) with one watt of energy. If you download the list of certified ceiling fans in Excel format, you can easily sort for the most efficient EnergyStar certified models. Here is a summary of the top three contenders as of February 2014:


There are plenty of other efficient ceiling fans on the EnergyStar list. But after my big time-waste tracking down an EnergyStar efficient range hood, I acquired an attitude. If I can’t find a product listed on the EnergyStar list in a simple online search, I move on.

Back to the top three contenders that were all easy to track down. The Haiku and MidwayECO are built with the efficient and very quiet electronically commutated motors (ECM’s). I assume that the Aeratron is also powered by an ECM, but couldn’t find corroborating information in the specifications.

The Aeratron is a ceiling fan unit only, while the Haiku can be fitted with a 1,500 lumen LED light module. The Midway ECO comes with a light module that takes four LED or CFL bulbs with the GU24 pin base. Tthe typical light output would be around 3,600 lumens. The Haiku can be dimmed as can the Midway ECO, as long as dimmable LED or CFL’s are used.

Prices for the models vary widely as of February 2014:

  • Haiku from $825 to $920
  • Midway ECO from $476 to $529
  • Aeratron from $224 to $349

Because we need dual functionality from our ceiling fans (air movement and light), the Midway ECO emerged as the best contender, even though it is still a very pricey piece of equipment.

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Price check, and – surprise!

I needed more rock wool insulation – a whole lot more. It’s for the second floor exterior walls and the attic.

My primary rock wool supplier, the Chicago Green Depot, went out of business about a year ago. I needed to find a new supplier!

Back in the day, the Chicago Green Depot had the best priced rock wool. I got the last batch in early 2012 for around $35.00 per bundle (60 square feet of 3 1/2 inch rock wool batts). All other sources I contacted, including your typical big box home improvements stores, always came in more expensive.

This time around, April 2013, didn’t seem to be any different. The Home Depot had the bundle of rock wool listed for around $43.00! I thought, though, that it couldn’t hurt to double check the pricing for 120 bundles at the Pro-Desk in my local store.

The printout I was handed listed a total of $3,340.80. That breaks down into a unit price of $27.84 per bundle plus tax (or $0.13 per board foot). That is a considerable price drop from the listed $43.00 … around 35%! This is even less that the first batch I bought for the basement installation.

Do I need to say that I was a very happy camper?

Why that 35% price drop? If I go to the Home Depot and place an order over $2,500, I am referred to – what they call – the bid room. Because I am buying in bulk, I have access to a different pricing structure. That said, I would be surprised if that 35% discount will last for long; this may be part of a current promotion.

The significance is that this is the first time that I bought a substantial amount of building materials from a typical big box home improvement store. Materials for a deep energy retrofit like ours were in the past not available, hard to get special orders, and/or too expensive.

Is this a sign that green building materials are on their way into the mainstream?

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Summer heat or summer freeze?

With the summer heat and humidity upon us, it is nice to escape every now and then the mugginess and soaring temperatures. Escape into a slightly cooler space, except that those spaces are impossible to find.

I think this is a recurring summer topic. Last year, I wrote that instead of cooling off some, we are sent into a deep freeze. I dread stepping into and out of any grocery store, which usually has been turned into one giant freezer. Going to the movie theater requires extra warm clothing in order to avoid hypothermia. The first thing we do when stepping into a restaurant or bar is scoping out the location of the air vents in order to find a seat that is outside the reach of the freezing draft.

I wrote about the industry standard for air conditioning including the recommended temperature ranges, and contemplated the need for a more adaptive approach. An approach that sets indoor temperatures somewhat proportional to outdoor temperatures, making the transition from the outdoors to the indoors much more pleasant, and less like a temperature shock.

The constant transition from the outdoor 90’s into the conditioned mid to lower 70’s cannot be good for our physiology. Or is it? Well, that’s what Google is for.

I searched for negative health effects associated with air conditioning or excessive air conditioning, and found … nothing!

All I found were references to excessive heat and associated health risks; or the spread of bacteria and mold spores through AC systems or reported cases where Legionnaire’s disease has been spread from cooling towers. But nothing really on the effect on our physiology.

I tried something else: I Googled the same subject in German. Et Voila, (pardon my French) I stumbled on a couple of references to sources that discussed the issue of temperature differentials between air conditioned spaces and the outdoors, and associated health issues.

One recommendation that showed up a couple of times, was to restrict the differential to 10 degree Fahrenheit. Admittedly, this has to be set into the context of central Europe, which doesn’t all that often match our Midwestern summer temperatures.

The German web references also mention that the transition across a broad temperature differential makes our circulatory system work extra hard. On reference compares it to a sauna experience, except that in the case of the sauna the cooling down time is relatively short, followed by a resting time in a normal temperature environment. Plus the cycles from hot to cold during a sauna experience are typically limited to two or four times.

Running a number of errands during a hot summer day can in fact exert more stress on our physiology and circulatory system than a typical sauna visit.

Now, why is it that this is not discussed in the English language? Or is it just me, doing a lousy job on Google? Have you come across serious articles and publications that address this topic? If so, I really would like to know about it! Please leave a comment.


1st floor ventilation fittings

The last post concluded with a few thoughts on material choices. Maybe I should start this post on the same subject – materials – but with a focus on duct fittings and accessories.

I was surprised how hard it was to track down some of them. The items that caused me real difficulty were the eight inch diameter butterfly dampers, an eight inch diameter wall hood and an eight inch diameter roof cone.

For a while, I thought I was looking in the wrong places. But after having contacted a whole slew of HVAC suppliers, I still had no luck. After hours of research I ended up buying what I needed from a variety of specialized suppliers.

Wouldn’t you think that these are more commonplace? Apparently not.


1st floor ventilation planning

I described the 1st floor range hood preparations, which had to get done prior to the spray polyurethane foam (SPF) insulation.

The other ventilation items we had to complete were the Energy Recovery Ventilator (ERV) supply and exhaust, both of which also required holes through the masonry walls for the duct work.

But before I get any further into the installation process, let’s take a step back and look at the rationales and design of the ventilation system.

Why ventilate

Ever heard of ‘sick building syndrome’? That’s when a building does not get sufficiently ventilated. The indoor air becomes stale and unpleasant. Pollutants and toxicants begin to accumulate and impact our health.

With a super-insulated and air-tight building envelope, proper ventilation is very important to us to ensure good indoor air quality (IAQ).

One may conclude that along with ventilation comes an energy penalty. The conditioned, stale indoor air is exhausted from the building while unconditioned fresh air is drawn into the building to replace it.

The gadgets

To minimizing this energy penalty the Energy Recovery Ventilators (ERV) or Heat Recovery Ventilators (HRV) become handy. They are basically air-to-air heat exchangers, taking the energy from the conditioned exhaust air and transferring it to the unconditioned supply air. I now get the fresh air I need for ventilation at a minimized energy loss.

I described the research and design that went into the ventilation system for the garden apartment. That blog post is a good overall introduction, and we can reuse almost all of the same principles for the 1st floor unit. The biggest difference between the two units is that on the 1st floor we have many more rooms to ventilate — nine rooms and two hallways to be precise.

The layout

To get good airflow we will need a distribution network of ducts.

The Ventilation Guide by the Building Science Press came in very handy again. It provided good guidelines on the layout options for the duct network, based on how we distribute our supplies and returns of the ventilation system.

  • Supply: point where fresh air is supplied from the duct work into the building, typically through a ceiling diffuser.
  • Return: point where stale air is pulled back into the duct work and exhausted from the building.

We overlaid the ventilation guidelines with our floor plan in search for the most thorough air distribution and exchange. Allotting the fresh air supplies among the entrance hallway and three bedrooms would give us the best results, if we placed the returns in the two wet rooms. Those would be the full bathroom and the future half bath.

To get the supply air moving from room to room, we have three options.

  1. To undercut the doors between rooms by up to one inch. We plan this for the French doors between the entrance hall and library, as well as for the pocket doors between the library and living room.
  2. Using ‘In-door Pressure Balancers’ where we would like the airflow close to the floor. This could be in most other regular doors.
  3. Using ‘between room vents’ where we would like the airflow closer to the ceiling. The In-door Pressure Balancer and between room vents can be used in lieu of each other or in combination.

Ventilation central

To keep the duct runs short, we converted the old hutch opening between the living and master bed room into a ventilation closet. Locating the ERV here places it right next to the old chimney flue, into which we would like to place the exhaust duct.

The more central the location of the ERV, the shorter the overall duct runs, the less the airflow friction and the more efficient the system.

The duct work issues

One problem we have is that the interior architecture does not lend itself to duct work. Six inch round ventilation ducts traverse the dining room or living room ceiling would look out of place.

We are fortunate to have ten foot tall ceilings throughout the 1st floor. These give us the opportunity to hide the duct work to the supplies and from the returns in the ceiling if we lowered it by eight to ten inches, depending on the duct sizes.

But we also would love to keep our ceilings 10 feet tall. After some back and forth, we determined that the most public rooms (library, living room, dining room and kitchen) should keep their ten foot ceiling.

The bedrooms, bathrooms, hallways and closets would accommodate the duct work and end up with slightly lower ceilings.

No matter what duct layout I looked at, I always ended up with a short run through the living room. We thought that if we keep that duct as close to the wall as possible, we could hide it in an elegant soffit right above the door.


Duct sealing

I mentioned in the last post that we sealed duct seams and connections. The subject of airtight duct work is rarely mentioned outside the green building community, but can be rather important.

The basics

When ducts get assembled, seams and connections are typically secured with small sheet metal screws. The screws don’t make airtight connections, though. Quite the opposite. These connections freely leak air, which can lead to substantial energy losses in the case of a forced air or air conditioning system.

If the ducts are used for a ventilation system, as in my case, leaking ducts can cause pressure imbalances and prevent sufficient fresh air delivery to the point of supply, rendering the ventilation system and needed air exchange ineffective. In other words, I would use electricity, for which I have to pay, to move air around in unexpected places and without getting the desired results.

The problems don’t stop here. Exhaust air that is returned from wet rooms such as a bathroom is often laden with moisture. Leaking duct work allows that moisture to escape back into the building where it can cause significant problems, such as condensation leading to mold growth.

In recognition of these issues, the 2006 International Residential Code (section section N1103.2.2) and the 2004 International Energy Conservation Code (section 403.2.2) require duct work to be substantially airtight or sealed, respectively.

The problem is that these code requirements are rarely, if ever, enforced, unless we are talking about a green building project.

What can I use to seal my ducts?

The first thing that comes to mind is, of course, duct tape. BEWARE! The pervasive duct tape, the silver stuff that is used to literally fix everything, is actually not suitable for ducts! I don’t know how it got this name.

Some research brought me back to GreenBuildingAdvisor.com, one of my web resources. Here I found a very informative blog post that covered the subject of suitable materials for sealing ducts.

I learned that real duct tape must be UL listed. But I also had learned from Mariusz, my plumbing and heating contractor, that even the real duct tape is likely to come loose at some point, because it so difficult and time consuming to clean all surfaces first.

The blog post corroborated Mariusz comment, and pointed to duct mastic as an alternative. Putting my sixth sense to this, I decided that duct mastic would be the more reliable and longer lasting option to seal my ducts and keep them airtight.

Putting things together

The application of the mastic is very simple. I used a paint brush to put a coat of up to 1/16 inch over the seams and joints.


Most elbows and reducers are not made out of one piece but rather several sections. The connections of those sections are not airtight either and it is a good idea to apply a coat of mastic here too.

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As you can tell from the pictures, these ducts with the mastic are not the most attractive things in the world. That doesn’t matter in the storage rooms or corridor.

For the living space, we switched to spiral ducts, which are much nicer to look at. These ducts come pre-assembled, are much sturdier and more expensive than regular ducts.

But, they don’t require any mastic or tape for sealing!

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The ducts get connected with couplings that have neoprene gaskets on either end. This allows for a very easy, presentable and airtight connection.


Soil gas, radon and health

I am moving down on my basement floor to-do list. The next task, the installation of the soil gas pipes, is all about health.

We spend the majority of our days indoors, yet we are not paying much if any attention to the health of those indoor environments. The indoor air quality (IAQ) of many work and living places is pretty lousy.

The green building movement is trying to change this by raising awareness of the IAQ issue. Poor IAQ can lead to low productivity at the workplace and health issues at work and at home. And we all know is that medical bills can be pretty expensive.

After having done some research on the radon issue, and after having decided that we will turn the basement into a garden unit, we realized that the installation of a soil gas pipe system for radon removal is an incredibly cheap IAQ insurance.

How does it work? I have four strands of 2 inch perforated, rigid plastic pipe traversing the basement. The strands are connected to a 4 inch perforated collector pipe.


The rigid plastic pipes collect any radon from the center portion of the basement. The perimeter drain, a flexible, perforated pipe, can collect any soil gas along the basement edge. If I connect it to the rigid plastic pipes it would perform double duty, keep the foundation wall dry (which also improves IAQ), and assisting with radon removal.


I like the idea of double duty and so I connected the 4 inch perforated collector pipe to the perimeter drain. The collector pipe lines up with one of our chimney flues, through which we can vent the soil gas removal system.


I prepared the chimney base, extended the collection pipe and left a stub to which we can connect the vent stack that will extend to the roof.


If I terminate the vent stack a few feet above the roof line with a material that readily heats up in the sun, I can rely on the negative pressure of the stack effect to draw soil gas out of the system from under the basement slab. I let thermodynamics do the work for me. I love it.


Zoning – the process

The zoning issue we really have to worry about is the side yard setback violation. I learned during the initial review that we can apply to have the side yard setback reduced through a process called administrative adjustment.


I have to submit a site plan, building elevations, floor plans and a recent survey for review. The survey can’t be older than 60 days!

Since the last permit for our property was issued in 1960, I was asked to get copies of property deeds prior to 1960 from the Cook County Recorder of Deeds. The point of this exercise was to compare if the legal property description on the deeds matches with the current survey.

Equipped with deeds from 1954 and 1953 I went back to zoning for due diligence on property description and side yard setbacks. During that same review I was asked to remove the bathroom and front door from the basement. Because our plans show the building with two units, anything that may facilitate a third unit (i.e. a garden apartment in the basement) was not permissible.

A zoning officer wrote up the subject of the administrative adjustment (called written denial), which I have to get notarized along with a number of other forms.

Formal application

I was not happy! We thought about converting the basement into a garden apartment sometime in the future. Removing the bathroom and front door seemed utterly counterproductive. That said, I did understand where zoning was coming from.

Back home, I could not get myself acquainted with the idea of giving up the bathroom and front door. Instead, I took a deep dive into the zoning code. Lo and behold, I found article 17-13-1003-BB Additional Dwelling Unit:

“In the case of building permit applications for the repair, remodeling, and/or alteration of buildings that have been in lawful existence for 50 or more years, containing not more than 6 dwelling units, sought to correct Notices of Violation cited by the Department of Buildings, or for the voluntary rehabilitation of such structures, in which there is evidence that the building has been converted, altered or used for a greater number of dwelling units than existed at the time of its construction, the Zoning Administrator is authorized to approve an administrative adjustment to make zoning certification of the increased density, not to exceed more than 1 unit above its original construction, upon review of documented evidence supporting such increase in density.”

Great, if we already have to deal with an administrative adjustment, let’s see if we can add an additional dwelling unit to it!

I went back to zoning armed with a printout of the article and was allowed to add the third dwelling unit. We updated the written denial and I paid the $250 fee for the adjustment.

Notification of adjacent neighbors and the alderman

Next, I was handed three form letters that, as in the written denial, described the zoning changes (i.e. reduction in side yard setback at the back porch and addition of a third unit). The three letters went by certified mail to our adjacent neighbors and the alderman.

I received the delivery receipts of the letters to our neighbors within a couple of days. Not so for the Alderman. It turns out that the letter was delivered after business hours. The Postal Service left a pickup notice, which sat in the Alderman’s office for days. It was only after my probing that the letter was finally picked up.

To be fair, this time at least somebody picked up the phone, responded promptly to my request, and followed up with me!

Review period

With all three delivery receipts in hand, I went back to zoning and was asked to return in 15 business days.

The rule is that our neighbors and the alderman have 10 days to indicate any objections to our administrative adjustment. The Department of Zoning and Land Use Planning (DZP) has another 10 business days to process our case upon which a final decision is made.

Well, 15 days is certainly better than 20, but still, it looked like our permitting process was dragging on far longer than I had planned.


Insulation – how much is needed?

We figured out that insulating the building from the inside with spray polyurethane foam (or, in short, spray foam) is the most suitable approach. It avoids potential conflicts with our masonry shell and will help with the moisture management in the brick walls.

The next question is: how much insulation do we need? We can look at it in terms of R-value (thermal resistance) or the depth of the spray foam layer, although both are somewhat proportionate to each other.

Here is what the building code says: R-49 for ceilings, R-19 for exterior walls and R-10 for basement foundations (Chicago Building Code, Chapter 18-13-102.1.1; Building thermal envelope insulation, Table 18-13-402.1.1). The Chicago Green Homes program requires R-52 for ceiling, R-21 for exterior walls and R-15 for basement foundations.

Having our eye on the zero-energy goal, it appears that more insulation or the highest possible thermal resistance is better. But there are limitations we have to wrestle with.

To keep the moisture management of the masonry shell intact, the whole interior wall assembly must have a perm rate of greater than 1. Closed cell spray foam has a better thermal resistance than open cell foam, but also lower perm rates. Limiting the closed cell foam to a 1 inch layer followed by open cell foam should yield the right perm rate and allow for the needed diffusion of water vapor through the wall assembly.

And then there is the space limitation. The building originally had no insulation. There was the outside masonry shell, a ¾ inch furring strip, followed by a ¾ inch wood lath and plaster assembly, which we removed.

Replacing the old 1 ½” interior wall assembly with 1 inch of closed cell foam plus dry wall, would only give us an R-value of around 6.5. Adding more insulation, beyond the 1 inch, would take away from the room size. Here are some scenarios:


My friend David Lemair knew about our effort to balance room size with R-value and pointed me to an article in Fine Homebuilding. I learned that spray polyurethane foam has a point of diminishing returns:

“… you would think that an R-40 wall full of spray foam would perform twice as well as a wall sprayed to R-20 with the same foam, but that is not the case.”

Source: Yagid, Rob; Spray Foam – What Do You Really Know?; Fine Homebuilding, June/July 2009

The article goes on to explain that the increased effectiveness from the R-20 to the R-40 wall is only about 2%. Open cell foam apparently reaches its point of diminishing return at 5 inches, closed cell foam already at 3 or 4 inches. No technical explanation is given to what causes that diminishing return, but I would really like to know!

The puzzle is coming together. We have determined that the closed cell foam must be limited to 1 inch to keep the perm rate greater than 1. It looks like open cell spray foam has its point of diminishing returns at 5 inches. That would give us a 6 inch insulation assembly with an R-value of about 24 that takes 4 ½ to 5 inches away from the room size. This is a good balance between R-value and room size.