Air Leakage of Old House - Does it matter?

*** Update - Upon further reflection of this topic, I do feel there is one additional reason to perform energy upgrades and discuss it in my project journal http://www.theenclosure.ca/windy-house ***
 
This blog entry will analyze the air leakage of a 1954 house and relate that to the energy use and durability of the house.

Before I started tearing down my 1954 single storey 1500 sq ft bungalow to make way for theEnclosure.ca, I decided to have the house tested for air leakage by Michael and Deborah from H&H small home solutions inc (hhsss at shaw dot ca).  H&H typically perform leakage testing to determine the EnerGuide rating for new construction, so this was going to be a new experience for them (and their blower door).

They came by in late March of 2014 after I had moved out but before I had completely emptied the house and before any deconstruction had been performed. The house was prepped by sealing the wood burning fireplace insert, range hood, and the through-wall mailbox before setting up the blower door.

We first ran the door in a B configuration and were unable to get up to the final test pressure of -50 Pa. But even in this configuration we got some scary results.  I had not really made any great attempts to air seal this house over the years.  There was weather stripping on 1 of the 3 doors, and the cedar siding had each coarse sealed to the next and the siding sealed to most of the window and door frames. But no attempts had been made to seal the interior interface with the attic plane and 1 of the doors had a cat door in it and the main door itself had very large gaps around it.

Prior to starting the test I had predicted an air leakage around 8-10 ACH (Air Changes per hour) @ -50 Pa, but early in the test we could tell it was going to be well above this. Deborah could tell just from the sound the fan was making (there previous worst house they tested was 11 ACH @ -50 Pa which was scary as it was new construction).

Right off the bat we reached 28 air exchanges at only -15 Pa!  To give you an idea, 15 Pa relates to a wind speed of only 11 MPH.  In the fall, I regularly recorded winds speeds on the property at this speed or higher so during those events all of that CONDITIONED air in the house was potentially changing over 28 times every hour. That is a lot of extra load on the heating plant and also explained the drafts my wife typically was feeling.


Over the next hour or so we tested at various configurations until we ran the fan at full open configuration (no restrictor plates). Only then could we get enough air volume to allow us to reach the target test pressure of -50 Pa.  AT the full test pressure we recorded an air leakage of 21.74 ACH -50Pa.

Now wait, some of you may have noticed that that is less air leakage than what we observed at only -15 Pa.  How is this possible you say?

Well, it is actually quite common.  As more and more negative pressure is placed on a dwelling, the two surfaces on each side of an air path (leak) can start to come together.  Eventually they can close up tight and stop that leak.  This why I have a bit of an issue (actually quite a bit), of testing dwellings at -50 Pa.  This relates to a wind speed of 20 Mph which is much higher than some locations would experience on a regular basis and much lower than other locations average wind speeds.  As such, it is my opinion that their should be a standard test pressure PER geographical region.  This could be a table much like the climate zone charts, but would be based on the average yearly mean wind speeds for a specific area.  Homes in higher wind speed regions should be tested at higher pressures than homes in lower wind speed regions.

(Side bar - the reason the wind speed is important is that it is this force that will effect the pressures on a dwelling.  Yes a house can depressurize under mechanical ventilation, but these are usually infrequent where wind depressurization or pressurization of the dwelling could occur for months at a time in windy locations).

So - these tests showed that the house was VERY leaky.  What does that mean in terms of heating bills, comfort, and building durability.

Heating Bills

The truth is, this air leakage did not really make a huge difference in energy costs.  My heating bills (for space and domestic hot water) were typically well under $2000 a year (We are under $2000 for both gas AND electrical use).  As I am a heavy bath user, it is safe to say aprox 40% of this was domestic hot water use.  This leaves an estimated $1000 in annual space heating costs.  That works out to less than $100 a month, or well less than the cost of a weekend dinner out.

We typically had the heat set for 72-73F in the wintertime and basically did not tough the thermostat all year.  It was not uncommon for the heat to come on during cold late spring and early fall evenings.  We did however use a programmable thermostat that was set to come on at 7 AM, step down to about 65F at 8:30 AM, come back to temp at 4 PM, and step back down to about 68F at 11:30 PM.  This was only partially for energy savings.  The night time set backs were used because we had hydronic heating through large built-in wall registers (1-2 per room) via a 1980's gas boiler.  The pipes went through and rubbed on the wood sub-floor assembly, so if the heat came on during the night the 'clicking' would wake me up.  So we partially closed the bedroom door (so cats could still get in and out and not cause another source of nighttime wake-ups) and used an electric oil heater to maintain a comfortable temp in the bedroom.

While air tightness is important, it will not make a huge difference to your pocket book unless you have a very large and leaky house.

Comfort

The air leakage did however make a big difference in occupant comfort and should, in my opinion, be the biggest (and probably only) reason to upgrade an older home.  The house was uncomfortable to sit in near any exterior wall in the winter months due to the drafts present.  I was quite surprised when I saw how leaky the fixed, but home made, windows in the living room were.  The builder had just placed the single pane of window glass against a wood surface and clamped it with a second wood component.  At -15Pa, the wind just whistled through these locations.  There is no question, that making the house more air tight would have made the house more comfortable.

Durability

Normally when one discusses the reasons for making a dwelling air tight, it is in the context of a 'modern' home with current levels of code required insulation.  With modern levels of insulation, it is critical to ensure that air leakage does not occur, in order to prevent interior air leaking into the wall or roof assembly and condensing on cold sheathing.  Left unchecked, this will often lead to mold and rot within the assembly.

The key here is the qty and location of the insulation.  As soon as enough insulation is placed inside of the sheathing to allow the sheathing to cool down below the dew point of the interior air, you now have an assembly with a very high liability should any appreciable amount of air leak into that assembly from the conditioned interior. This is because air currents are the #1 mover of moisture next to bulk water leaks caused by plumbing leaks or incorrectly detailed cladding or roofs that permit bulk rain water entry into the assembly.

But in older houses like the one I took down (which had ZERO insulation in the walls), there is not enough insulation present to block the heat loss from the house enough to allow the sheathing to get to the dangerous dew point conditions.  If you never reach the dew point, you can have huge amounts of moisture moving into the wall via air leakage and never have to worry about it because it stays in vapour form and just moves on through either to the outside of the dwelling or back into the inside. There is never liquid water that results from this air leakage. This is the reason why older homes have performed so well over many decades without the presence of air barriers, vapour barriers, or even effective water shedding surfaces.  The heat loss has always been enough to 'cook' any accumulated moisture out of the assembly.

Conclusion

We have identified in this article that there is not a huge financial penalty for a leaky house.  In my case, the costs per month for space heating were under $100/month in what is considered a cold-heating-dominated climate.  This $1200 annual investment would not get very far in paying for a deep energy retrofit which typically would cost 10's of thousands of dollars.  Lets say you could reduce the heating load even as much as 75% (purely speculative and most likely could not meet), this would represent $900 annual contribution to renovation costs.

A REALLY cheap stud level renovation for my home (including new windows and doors) would have been at least $60K (going to need to rip out parts of bathrooms and kitchens so most likely will totally renovate those rooms - my budget of $60 assumes very low end cabinets for these rooms).

A very intensive attic floor plane sealing regime would have been at least $15K (not going to do this process without bringing attic up to current insulation levels when done).

At a highly inflated $900 annual savings, these two projects would have a 66 and 17 year payback respectively. The attic plane sealing payback would most likely be much longer as only sealing this plane would probably represent only 50-70% of all air leakage present and therefore there would be reduced energy savings.

And my house did not represent an unusual annual energy bill. This US Energy Summary shows that for the West, the average annual winter heating bill per household varies between $1300 and $800 depending on year.

In the end, due to our really low energy costs, and the likely hood that they will not appreciably escalate for many decades due to Government interference, it makes very little sense to upgrade an existing homes energy performance for personal financial savings.  Therefore the type of renovation needed to reduce air leakage or increase thermal performance, only makes sense if the home is being renovated anyway for cosmetic or occupant comfort reasons.

On a separate track - this logic also holds true when analyzing extreme new construction programs like Passive House.  The costs to reach passive house levels of energy reduction will not be paid back over the lifespan of the dwelling in most cases. The added detriment of these programs is that the embodied energy of the insulation products built into these dwellings also do not have a pay back within the lifespan of the dwelling.  Instead for new construction, it makes more sense to build a "Pretty Good House" (coined by Joe Lstiburek) and then use the excess capital available to either contribute to distributed or on-site energy generation.

It is however critical that air leakage be reduced down to a minimum (experts do not agree how little is adequate - but the number is somewhere between 1ACH+/-50 and 3ACH+/-50) for new construction or energy retrofits IF, you have built an assembly with enough insulation inboard of the sheathing to cause the sheathing to cool down to the dew point potential of any leaking interior air.   If you build a safer assembly with the insulation outboard of the sheathing (or enough outboard to maintain the sheathing above the dew point potential), then while air leakage is still important to address from an energy loss standpoint (the costs to get it right during construction are minimal and will be paid back by reduced energy usage), it usually will not cause a durability concern for the assembly.  This of course is all from the perspective of a heating dominated climate.  The direction of flow and order of layers for the assembly are different in a cooling dominated or mixed climate.

Alfie Lives

Well Alfie did not exactly get the life of leisure I promised him.  I immediately put him to work on my 'rock pile' in the back yard that was hidden under years of blackberry growth.

Start of job - find the rocks and dirt through the mountain of blackberries and ivy!

 A lot of rocks to screen.  This is excess soil and fill that accumulated from previous projects around the yard like the perimeter drainage, garden sprinklers, and the start of a waterfall, pond and stream.

Not exactly Kutny's Soils scale, but it worked wonderfully.

The finished screened pile (about 20 cubic yards worth) - I have a lot of stone work in my future.  Plan on a stone wall fence, stone wall raised garden beds, stone herb gardens, and a selection of stone and gravel stream bed.

But just before getting to the above finished stage, poor Alfie had to have a rest.  He had been leaking fluids before I liberated him, but the vendor had thought they had addressed the issue by flushing and cleaning the radiator.  Well the problem was a bit more terminal than that and poor Alfie required bed rest for the last 3-4 weeks while we searched for a suitable heart donor.   A suitable replacement water pump was located last Friday and Alfie went under the knife last Monday.  After 4 hours of anticipation and worry, wondering if he would or would not make it, Alfie woke up and jumped out of bed and started digging.  

After looking at the pump that was removed, we are amazed that it was still in one piece with the cracks radiating around the entire perimeter.  We are thrilled with his recovery to date but he is not out of the woods yet.  He still gets flushed after a few hours work and needs to take a break to cool down.  We will work together to get through this season and then he will go see a specialist.  We are all routing for him here at SENWI.

Time to Realize a Dream

So what started all of this?  What is our need?  Why do I need to change anything?

Well, our 1954 bungalow has been showing its age for as long as we have owned it.  My wife and I have struggled with the appropriate way to move forward for years.   Do we renovate the existing structure, add on, or start from scratch?

Yes, we could just renovate the existing structure to make it ‘pretty’ for us and generally satisfy our ‘needs’, but this would not address the fact that many of the systems within the home are reaching the end of their service life.  So the renovation would need to be much more extensive and would have to include new domestic water supply and waste drains, new windows, insulating all exterior walls and increasing the insulation in the attic, replacement of the hydronic radiant piping going to the wall registers (which means replacement of all of the flooring).  If this amount of work is being done, I would be foolish to not also re-wire while I had the chance.  This would most likely set us back somewhere around $100K in today’s construction costs with me providing most of the labour.

But then we would still be left with a 1500 ft² 2 bedroom dwelling that does not represent the ‘highest and best use’ of the generous 73’ x 146’ property in an urban area where most buyers are young families needing 3-5 bedrooms.  As a result, whatever we did to the existing dwelling would likely not save it from the wrecking ball if we sold it.  I have a problem with sinking a sizable pot of money and resources into something that would still be thrown away if we ever sold.  It does not, to me, feel like a wise use of limited resources (both ours and the planets).

Aside form the ability to sell the dwelling; I also feel it is inappropriate to create a house that would only be sized for two people.  I have reviewed some of the concepts of architect Frank Lloyd Wright who did encourage homes to be built “just big enough” for the current occupants and “expandable” for an increase in occupant load.  However, when you look at the details, this does not seem to be practical method in my view.  It is very difficult (close to impossible and very expensive) to build an ‘expandable’ home and still meet best practices when it comes to building a bullet proof building enclosure not to mention a properly laid out and sized space and domestic heating system.  Unless the house is enlarged at the same time periods the existing mechanicals were worn out, I would be removing components that had life left and wasting the embodied energy that went into making those products.  I feel instead that multi-family dwellings are much more appropriate to build for 1 or 2 occupants and will easily fill this need in our society.

It is more appropriate, in my view, to design a single family dwelling that looks to the future to predict possible uses and is then built with as much flexibility as possible to meet those needs for the next 50 to100 years.  If this kind of structure is then designed in a durable and highly energy efficient design, I believe you have now achieved the lowest overall carbon footprint for not only your use of that dwelling, but also that of its future occupants.  You would have designed and built a legacy instead of a liability.

So, I need to build a new or heavily modified dwelling.  Now what?  Well, if I am going to build a home, then why not built it to incorporate the best of all of the various ‘sustainable’ programs currently available. Build it with foresight; looking at the ‘operating costs’ when making build decisions and not the short term ‘build costs’.  What are the operating paybacks to putting in better windows or higher levels of insulation? It is all fine and dandy to say I want an energy-efficient, low-carbon footprint, durable and sustainable home, but if I cannot afford to build it, it is not going to happen. 

We have a limited budget for building, and my wife does not completely share my passion for all things ‘sustainable’.  So throughout this process, I will need to make hard decisions on where the biggest bang for our buck will occur.  I will focus on making the long term components (the foresight I was talking about) of the home the best they can be (structure & building envelope) and only install ‘affordable’ short term components (plumbing & electrical fixtures, appliances, and furnishings).  These are all items that are renewed several times throughout a dwelling’s life and so can be upgraded at a later date as desired and as affordable. For the mid term components like the heating systems, I will try to design as efficient a system as possible that can be modified in the future to be even more efficient (like including solar capturing or solid fuel burning systems).

So it appears an exiting new chapter in my life is starting to unfold.  A realization of a dream that started 40+ years ago.  As I start down this road, I have realized my need for learning will never be quenched and that unless I analyze and challenge the decisions I make on a day-to-day basis, I will not be able to ensure that I make the right ones.

I would like to charge you, readers of this blog, to provide words of encouragement, advice, and even critique.  And in the meantime, I hope that each of you enjoys taking this ride with me as I document my personal journey in the realization of this amazing dream.

School is Over!

Here is the next installment of how I came around to wanting to build and live sustainably.

High School is now but a distant memory and I never need to learn again, right?  Now what?

Well, I had trained to be a carpenter, so let’s get going.  I came to an agreement with a Journeyman working on a dwelling a few doors down from where I was living in Richmond.  I just needed to sign the apprenticeship papers.  I had been working for this fellow for a few weeks as a labourer to get a feel for the ‘real world’.  On one particular day, I had spent many hours prying out 2”x12” Floor joists installed at 12” centres with a nail gun (they had been set at the wrong spacing and elevation - but not by me). That evening, I ended up in the hospital with a set of pulled back muscles, interrupting a Christmas get-together with my uncle’s family in Abbotsford.  I took the opportunity to re-analyze my career path.  My family members generally had a history of bad backs and I soon realized a life in construction was probably not a prudent course for me.  Looking back, with hindsight, this was probably one of the best decisions I have ever made, as I avoided the downturns of the construction sector throughout the 80’s and 90’s and saved my body for the project I plan today - 25+ years later.

So after a few part time jobs I landed up in a spot I would have never guessed.  I landed a desk job as a professional purchaser for a chemical engineering firm with plants all over the world.  I generally worked in a two man department responsible for sourcing and supplying spare parts and replacement equipment for our 60 plus clients at locations throughout the planet.  This was a good fit for me as I was given a LOT of autonomy and wore many hats.  I became known as the “efficiency natzi” during my 19 year career there because I was always looking at ways to make the processes more efficient.

The frustration I had for inefficient processes raised its head one day when I was asked to take over the logistics on a project that was almost completed and ready to start up.  Those in the business will know that this is when the most activity takes place and ALL shipments are RUSH shipments.  My frustration with a spreadsheet based shipping and logistics system reached a climax one day and I proceeded to become self taught in Microsoft Access data base design (I thought the learning part of my life was over – I already know everything - right?)  I created a program that took a process that previously took hours to prepare the data and close to an hour to just generate the print job, to a process that just required ongoing updates to the order data and then the press of a button when it came time to print the packing lists.  15 minutes later, the 100 or so page packing list was ready at the printer.  Not wanting to stop there, I then pressed to expand this system to include purchase order and requisition generation and was able to reduce information previously entered 3 times into different systems into only 1, saving hours of work and reducing errors.

It was while working at this company that I started to think about the bigger picture.  I saw the destruction that many of our clients were causing to the environment and to the residents living near their chemical plants.  And while many of the products designed by the company I was working for greatly reduced the impact of our client’s plants (we had a division that did nothing else besides producing processes and equipment that reduced the amount of nasties discarded by a plant), I still was developing guilt for what ‘we’, as a company, were part of.

It was also during this period at the beginning of the 21st century that I also started to make personal changes to how I impacted the planet.  At work and at home, I switched to a generally paperless system.  I started scanning all inbound paper so that it could be stored and retrieved efficiently in an electronic format (why continue buying filing cabinets).  I moved away from faxes and snail mail and now emailed most documents to all my vendors and clients.  The volume of paper printed by me had dropped by many factors and I was now able to retrieve information in a much more efficient format allowing me to handle larger volumes of work (sounding a lot like my high school projects).

I was now determined that no matter how small my contributions were, I was going to start making a difference!

Living Life in Vancity

A shout-out to a colleague (Alexis Morgan) who is also documenting his personal journey through renovating an older home in the East side of Vancouver into a modern and efficient structure to serve his family for decades to come.

Check it out at http://life-in-vancity.blogspot.com