Passive House Design in Canada Series of Articles Coming Up

Hi All,
I plan to begin a series of articles discussing Passive House design and general house design together.  I will be using our own project its specific design challenges and ideas to highlight concepts.  Here is the latest rendering of our design to date.  More to come on this.
LT

Preparing the Garden for Construction

Although this long winter seems never-ending, we know spring is just around the corner! To remind us of the greenery that is surely on its way, here are some photos of the garden in preparation for the eventual demolition of our house, and with it, much of the yard.  We spent a sweaty afternoon last June moving our beloved tree peony to a corner where we hope it will be out of harm's way during construction.  In a few weeks, we'll know if the many transplants survived the winter...
-PT

Before

After

A Buyers' Guide to HRV's and ERV's for Passive Houses in North America

HRV and ERV's
http://www.greenbuildingadvisor.com/book/export/html/16744

Why Stairs are Next to Front Entries

I often wondered why in so many house designs the stairs are placed in the front entry, and I was not alone in this bewilderment.  Family and friends have sometimes fumed at it.  Why would a designer place a stair to the bedrooms (a private place) next to a front door, (a very public place), sometimes so close there is hardly a place to take your coat off.  Plus, you have to tip-toe past this dirty area in order to go to bed or to come downstairs for breakfast......Sheesh!

Now that I'm the designer, here's the other side.

Reasons for having the stair in the front entry:

1. This often helps in making the top of the stair end up in the middle of the upstairs.  Why should this be so?  Because bedrooms are legally required to have a window to the outdoors for egress purposes.  (The most dangerous time when occupying a building is when the occupants are sleeping - so if there were a fire, sleepers have a window nearby as an escape alternative).  As such, all bedrooms must be placed against exterior walls.  Therefore, to make best use of space, the upstairs hall should be placed in the middle of the floor, and all the bedroom doors open from this hall.  One way this is made possible is by having the bottom of the stair near an exterior wall.  If the bottom of the stair is in the middle of the main floor, it can be a waste of space in the upstairs to create a long hallway to get to the middle of the upstairs, which will generally be required.  Now downstairs, there is already a circulatory area near the building extremity which is lightly used - the front entry - therefore, from a space planning perspective, it is often an ideal spot for a stair.
2. To put shoes on, it is nice to have a bench, but in terms of smaller houses, to make best use of space, the stair can double as a bench for putting shoes on.
3. The stair is the one place in a simple home where there is relatively more architectural interest.

Often, it also makes sense to place a stair close to an exterior wall, since it introduces an opportunity to have another entrance to the building from a different exterior grade, especially at a landing.  This is another good use of space....although space use efficiency need not always be the final determinant in design of buildings.  Check out this hardworking front entry to a Farm house - plans available on FreeGreen.com.  Stairs, full size closet, bench and shoe storage - all the needed items, plus two ways to get to it.  And, you don't really have to get your feet dirty to use the stair.  The only improvement I can suggest would be for the stairs to be in the reverse sense so the stairs to the basement are closest to the entry.  The entry is so well used, there is no space for a powder room door, or for windows.  Bringing light in from the Entry door's sidelights is therefore important.

Prices of Vacuum Insulated Panels

I was amazed to find a corporate website giving prices for their VIP's online - but I think its such a good idea.  The lack of price information on the internet is the major obstacle to optimizing designs of any products, including buildings.  Here is the link.
http://www.glacierbay.com/barrier_price.asp.  Price ranges from a minimum of about $30/SF USD, but goes by the number of panels.  Each panel is about $345, at a max of 30"x35", and $600 for a max of 60" x 70".  Glacier Bay also provides an excellent primer on this technology: http://www.glacierbay.com/support/library_docs/vacpanelinfo.asp



Given this information, I feel a vacuum insulated door with a window should be possible to market for about $2000.  I recently received some pricing for the Frostkorken VIP door and the price seems astronomical at something like 3times that number.  Major market niche is possible here for NA.
The other company providing VIPs is Nanopore.  http://www.nanopore.com/vip.html

Window Placement in a wall, Depth of Reveal, and Psi Install

During our Passive House training, we were told recent results are beginning to reveal that the best location for a window in the wall assembly is in the middle.  The isotherms (lines of constant temperature in section views) stay as straight as possible in this situation - their curvatures to meet the window glass from wall edges is minimized.  Reduced curvature in isotherms generally means reduced heat loss.  One might even say that the distance between isotherms is proportional to heat loss (flux), but I think it is more complex than that.  In the case of the vacuum insulated panel, the isotherms would be very close together simply due to the form factor, (they have an R-rating of about R-50/inch in IP units), but the heat flux would still be relatively low.  These details need elaboration, but I don't know much about it yet....

So are Deep window wells inside Passive Houses a good thing or not?

I have been fiddling with my PHPP and reading the 'research' and find I don't find a convincing argument that they are a bad idea, which I think some people are apt to say.  Very crude experimentation with the PHPP will show that window reveals are of major importance in determining the solar gains available to the building.  Thus, placing the window near the exterior can have major benefits for overall thermal perfomance of the building, despite less favourable psi-install values.  Note that the window configuration is of significant concern here.  Where you have a very large window surface, with lots of glass compared to the perimeter, the importance of the reveal depth is reduced, and the psi-install value may be highlighted as a potential focus for further heat loss reductions.  This may also be the case when the wall is not very thick.  But when you have a very thick wall (say 24" or 0.6m), and the windows are not too big (say 40"x72"h at most), then the depth of reveal plays a major role in the building's performance - I would say a larger role than the psi-install value.  Therefore, we can still sometimes have deep window nooks in Passive Houses in cold climates. 
With respect to isotherms, you will find that the corners where the walls and sill and heads meet the opening can be chamferred.  The isotherms at these locations stay well away from the vertices anyways, so chamferring the opening where the door is installed, for example, should be fine in terms of energy efficiency.

Updated Design

Here is our latest.  The building is rectangular, with a stepped gable roof.  The long south facade presents an improved oppurtunity for solar gains, but the north face is also longer, where more losses occurr.  Of course, a large part of the gable roof is available for solar collectors.  Outside dimensions at walls are 43' x 31'.  All walls are 24" thick, and insulation values are about R70 walls, R100 Roof.  All cellulose, with likely some mineral wool in the basement.  No rigid foams or virtually none.
The view is of the South and West facades.
To give the south facade untrammelled solar exposure, we've moved the main entrance to the West side.  the challenge we now have is to make the entrance obvious and inviting.  It is almost like having one of those snout-nosed garage designs, where the visitor must travel around the garage to reach the front entrance.  In this design also, he is to travel around to the side of the house to enter, all the while remembering the importance of solar energy!  We are playing with those West roofs, and may even make them somewhat enclosed.  The building has a small enough footprint, we have room to spare in the lot coverage allowance.  The East side faces the street, where there is a balcony attached to the 2nd floor master bedroom in that tower-like stone-covered end.  Below that is an adaptable space where an elderly couple can stay on the main floor - they have an entrance to the garden under the balcony.

View from the South West.

Aerogel Insulations

Found a place where you can buy aerogel.  The product is a pelletized aerogel, rated R-8/inch.  Cost is $160/5 gallons - super expensive.  They also make translucent skylights using this 'nanogel'- visible transmittance 20%, R-20 insulation.
http://www.solar-components.com/aerogel.htm

Geo-Solar Seasonal Heat Storage

Solar Thermal is great - but if you size the system so there is no excess heat in summer, the available heat in winter is pretty low.  So the thing we all want to do is store excess heat from the summer to use in winter, and store the excess cold from winter to use in summer.

Our yearly energy demand of the house is 3600kWh for space heating, and 4400kWh for DHW, total 8000kWh.

To store 8000kWh of energy as heat, here is one option:

• Not accounting for losses from time of heat input to time of heat usage,
• Store hot water in a Tank - say we can use water from 0 deg to 80deg C (delta T is 80K)
• Specific heat of water is 1.17Wh/kgK (=4.18kJ/kgK, as 1watt is just 1J/second).
• Volume of water (M) needed:  M = E/(C*delta T) = 8,000,000Wh/1.17*80 = 85,470litres
• thats a lot of water - a tank about 3m x 9.5m x 3m tall

We can improve this dramatically if we utilize the phase change of water from solid to liquid, since the latent heat of melting of ice is 92.8Wh/kg  (=334kJ/kg).  If we utilize the water from say a couple of degrees below zero to about 80 degC, the volume of ice/water required reduces to about 1/2 of what was before (about 43,000litres, down from 85,500)  but there is then the technical problem of dealing with the expansion and contraction of the ice - which I don't know how to tackle as yet.  You can imagine that a container about 3m x 5m x 3m tall can certainly fit somewhere on our city lot.

We can reduce the storage requirement further.  We don't need the capacity to store the entire year's energy demand.  Lets say we use the solar thermal system to it's max - then we just need to figure out what fraction of the energy needs are not met in winter, and store enough to cover that much. - surely much less than the 8000kWh.  Later, we'll also have to deal with the storage losses and system inefficiencies - so the amount of storage needed will probably end up near the 8000kWh anyway...!

Geo-Solar Seasonal Heat Storage and Other Information

I think this guy has the right idea. about Geo-Solar Energy systems:
http://ecorenovator.org/forum/solar-heating/999-seasonal-heat-storage-under-existing-house.html

Depth to Ground Water/Elevation of Water Tables in Toronto area:
This information is so far hard to find, but the below links might be a start...
I need this info to consider the thermal conductivity of the earth below and around the house.  This also has important implications for thermal energy storage in the ground.  A High Water table will mean foundation structural design will be affected and heat lost form the basement may be high due to the flow and thermal characteristics of groundwater.

http://ess.nrcan.gc.ca/2002_2006/gwp/p3/a1/index_e.php
http://gsc.nrcan.gc.ca/hydrogeo/orm/maps_e.php
http://geoscan.ess.nrcan.gc.ca/cgi-bin/starfinder/0?path=geoscan.fl&id=fastlink&pass=&format=FLSHORT&search=PUBLIST%3DSOH