New look, new logo… and a Permit!

I mentioned earlier that we (finally) got a permit from the building department.  What should have been a 2-3 week process, took 2 full months.  Why you ask?… there were a few hurdles, but the biggie was our choice of materials for the basement foundation.  There are a handful of options, but most contain concrete (a thermal-bridge extraordinaire!) and in the interest of minimizing this “high embodied energy” material, we looked for trust-worthy alternatives.  One rather neat alternative is Durisol; it’s a variety of ICF (Insulated Concrete Forms) that minimizes concrete use, and doesn’t use EPS insulation like conventional ICF solutions.  But if your goal is a truly thermal-bridge-free assembly, there is one product that really stands out: SIP or “Structural Insulating Panel”.   SIP wall assemblies have been around for many years and are quite common in high performance homes for above-grade applications.  What is a little less common, is the use of SIPs for below grade applications.  This product has also been around for many years… just not here in Kingston.  Unfortunately our building department views anything unconventional as a liability risk, even if it has engineers stamps, is backed by a phenomenal warranty, and meets the Ontario Building Code !!  This isn’t an ideal mindset for a city that is striving to become “Canada’s Most Sustainable City”.  Embracing innovation and change should be priority.  We have the permit, so it’s water under the bridge… ‘nuf said.

We struggled for quite some time with designing a logo for Kingston Passive House.  This project will be promoted, so signage is a must.  We think we have a winner – it has something for everyone:

logo-KPH

We’ve also cleaned up the look/theme of this blog… let us know what you think!

A Breath of Fresh Air

Have you ever lived in or visited a home and noticed curtains moving on a windy day?  Perhaps you have unplugged something from a receptacle on an outside wall and found the plug to be cold.  These are signs of a leaky house.  In older (and some newer) homes, this is how fresh air is introduced to the home.  So what’s the problem with a bit of fresh air?!  We need to think about this from two distinct but related angles: Indoor Air Quality (IAQ) and Energy Efficiency.

We spend quite a bit of time in our homes – particularly during the heating season.  As occupancy increases, more oxygen is removed, more carbon-dioxide is produced, and exposure to potentially toxic air is at yearly highs because we don’t have windows open.  Our cabinets, furniture, flooring and many other household goods, are constantly off-gassing; further degrading the quality of the air we breathe.  You get the picture…  not pretty.  In a leaky home, fresh air is introduced around doors, windows, lights, receptacles, rim-joists and many other avenues.  Bathroom fans and clothes dryers remove moisture-laden air from our homes, creating a negative-pressure which also draws fresh air in. Air is opportunistic that way and from a health perspective, that’s a good thing.  Even on a still day, the stack-effect will help keep air moving, but it’s not consistent and unless you have expensive monitoring equipment, you have no way of knowing what your IAQ is.

Fresh air is either forced in (wind) or drawn in and although good for our health, it presents a significant problem from an energy efficiency perspective.  That fresh air is either displacing or replacing conditioned air; that is, air you have already paid to heat or cool.  What we need is a means of regulating/controlling fresh air while capturing the energy from outgoing stale air.  Heat-Recovery-Ventilators (HRVs) serve that purpose and have been around for many years.  Most HRVs are installed so they draw air from smelly/humid locations (kitchen, bath, laundry) and deposit the fresh air into the cold air return plenum on the furnace.  In a Passive House we don’t have a furnace or an air handler (typically) so the fresh air is delivered to the bedrooms, family room, office etc. The HRV in a Passive House also runs 24 hours a day, not just when you hit the button before your shower.  This is an important distinction: Consistent, balanced introduction of fresh air is the secret to a much healthier home.

The HRV runs ’round the clock, it harvests heat energy from the out-going stale air, and the air quality is great;  so all is good, yes?  Not all HRV’s are created equal. A typical builder grade HRV is (at best) 50% efficient; only half of the energy in that stale air is recovered – the other half is lost.  If our goal is energy-efficiency, this is unacceptable. Typical North-American made HRVs have a cross-flow heat exchanger, and a small one at that. The fresh and stale air-streams pass through channels that are perpendicular to each other, so there just isn’t enough surface area to recover significant amounts of heat:

Cross-Flow Heat Exchanger in a basic HRV.

Cross-Flow Heat Exchanger in a basic HRV.

Increasing the heat exchanger size will help a bit, but to achieve > 80% efficiency requires a different approach:  Passive House HRVs have a counter-flow heat exchanger and they’re large.  The parallel air-streams and increased surface are make all the difference in the world.  Throw in EC (Electronically Commutated) blower motors and they won’t cost a fortune in electricity to operate:

More Efficient Counter-Flow Heat Exchanger.

More Efficient Counter-Flow Heat Exchanger.

As I write this post, I am aware of only one Canadian manufacturer of HRVs that incorporates a sizable counter-flow heat exchanger.  We were glad to find it, but it would be nice to have options, and going with a European model is not only costly, but not Canadian eh!  I’ll spare you the details of modelling an HRV in the PHPP software. Just know that it entails gathering all the performance specs, and that’s not a simple task considering North-American testing methods (www.hvi.org) are different from those in Europe.

There is one more rather unique feature of many Passive Houses that dramatically increases the efficiency of an HRV.  That’s all I’m saying for now, you’ll have to wait until my next post to find out what it is…

Windows in a Passive House – Part II

While the Passive House standard is (for the most part) non-prescriptive, there are a few areas where it makes sense to specify a certain level of performance based on your climate; windows are one such area.  In my last post, I touched on a few aspects of window design, construction and tuning,  as they pertain to a high performance home.  Here, we’ll look into why window details are so vital to the success of a Passive House in terms of behavior and of course, the PHPP.

As the adoption of Passivhaus spread to other regions of the globe, the Passivhaus Institute realized windows designed for a German climate were either insufficient or overkill in many of these differing climates.  You could argue that a window designed for central Europe would work just fine in the Southern US and you’d be right, but in the interest of keeping costs down it isn’t reasonable.  The PHPP modelling software won’t mind a bit if you over-engineer your windows; the problem is it might not mind if you  under-engineer them either.  PHPP will actually let you get away with double-pane windows in a Canadian climate if the rest of the building envelope is extremely well insulated and super-tight.  The software simply does the math; if you meet the monthly or annual heating/cooling load demands (among other things), PHPP will give you the thumbs-up.

If we think about the behavior of a double-pane window on a cold winter day in a Passive House, we’ll quickly realize why the institute has a minimum standard based on climate.  In an average home, there is a heat-source below almost every window; this heat source helps reduce effects of the cold draft and creates air movement to minimize the formation of condensation.  In a Passive House, the walls are thicker, so the interior glass surface is “further away” from room air currents. There is also much less of an air current because the heat demand is so low…  The result? A double pane window (with its cooler inner glass surface temperature) will create a cold draft and promote condensation; two impermissible characteristics in a Passive House.  Kingston is located in the “Cool Temperate” zone, making the minimum glazing requirement triple-pane thermal units with low-e coatings, argon gas fill and non-conductive spacers.  The overall U-value for these windows can be no more than 1.1 W/(m² K)  (lower is better), so the frame and installation details are vital too.  This calibre of window will have a warmer inner glass surface temperature, resulting in a more comfortable space with greatly reduced chance of condensation; It makes perfect sense.

PHPP calculates both heat losses and gains for each window in the house. To do this, it requires every intimate detail of your windows, including orientation, frame thickness, depth and insulating-value.  It also needs the center-of-glass and spacer conductance numbers along with the solar heat gain coefficient (SHGC).  On a different sheet, you’ll enter in the shading characteristics of window frame reveals, decks/balconies, overhangs and neighboring trees and buildings.  The software does the heavy-lifting in terms of calculations, but if you aren’t using Passive House Certified windows, you may have to do some digging to get the necessary performance numbers from your manufacturer.  North-American standards are typically NFRC (National Fenestration Rating Council), which are quite different from the CEN (European Committee for Standards) methods both in terms of what is measured and how.  We were fortunate that our manufacturer let us talk directly with the independent lab that did the testing on their behalf.  They had the numbers we needed for PHPP.

If it interests you, the Lawrence Berkeley National Laboratory offers (for free download) their comprehensive software simulators for insulating glazing units and frame assemblies:  WINDOW and THERM respectively.  They are fascinating bits of code.

On a closing note, I am delighted to be able to say that we (finally) have been issued a permit!  That was an adventure in itself; more on that later…