We are presently doing some deep rethinking of the design in floor plans to improve the use of the south-west floor areas and possibily reduce the number of exterior entrances from 3 to 2. Will present floor plans and other details after we get the permit. Meanwhile, experimentation with the roof has produced the following design with clerestory windows into the attic. No energy analysis has been applied to this increased exterior surface area and glass, but hopeful it will prove positive. I find the south facade too busy now, so this needs attention. One good thing energy-wise would be to remove the entrance from the south facade, as it gets in the way of the south glass. The west side would be a good place to have it - but perhaps thats too uninviting?

More experimentation with the roof. This design just below with the long balcony is the most developed with glass areas and overhangs carefully arranged to maximize solar gains in winter and shading in summer.

This humped-back design increases internal volumes, and improves the roof angle on the south facade for best use of solar panels. The turned-up roof bottoms provide the needed overhang over the south glass. Not sure how much I like the appearance - give us your comments! - LTI find this one quite interesting. It reduces the building's bulk at the street, which I think is useful, and introduces the gable peak as a delight a bit further back, bringing the window close to the attic spaces. The curved winglets play against the square form. Drawbacks include the much reduced ceiling heights in the main hall on the 2nd floor and a vacant-looking east exterior, which perhaps can be corrected with a wraparound south window.

Balcony and Curved Winglets

A balcony was requested and more whimsy on the roof so here are some more images of design experimentation. One issue with this roof is it needs to be centered on the building otherwise it looks odd. This places challenges on lot coverage due to the need for deeper overhangs on the south side. Can be resolved with projecting the east and west walls beyond the south wall.

North Facade

Here is a view looking south-west from the north. Note the lack of north facing windows to minimize heat losses. A major loss of heat was through the 3 entry doors on the house. To compensate, we've had to increase the R values in the roof, the foundation, and reduce the north windows. One problem I see with passive house design right now is the lack of high-performance entrance doors. They all seem too thin to me. Why not have thick vault-like (albeit not heavy) fibreglass doors with urethane foam insulation, thermal breaks, triple sealing on tapered edges and rounded corners so there is lots of insulation, continuous sealing, and heat losses and air leakage are minimized? I can't find one out there - perhaps I should look at marine applications. Would be happy to make them myself, but there is just too much to do!

Recent design changes

Recent changes to the model include adjustments to sizes, locations, and number of windows on the East and South Facades. East Windows lose significant heat, and West windows introduce a lot of it, so West windows need to be minimized to reduce summer overheating and East windows kept in balance to keep heat losses down.

The neighbour's house on the north side is now included as well.

Interior layout has received a lot of changes and the stepped roof fits well with it, in addition to adding some visual interest to an otherwise vast roof. The step will also simpify the provision of conduits and 'plugs' serving solar arrays on the minor roof.

Couple of renderings from Revit. Neighbours house on the southwest side is included. This first one is the rear, and the second one is the front again - South side.

Sun is modelled as at noon on the winter solstice, but it's probably off by about 15deg since I haven't adjusted the house orientation. The aerial view in the previous blog is aligned to true north, so you can see the streets are tilted pretty close to 15deg to the west.

LT

Aerial View

Thought I would post an aerial view of the existing property. The big round thing is a 13ft trampoline. Anybody want a trampoline? It's really going to get in the way. We also have a ping-pong table we need to get rid of.

LT

The below pic is of the existing house on the property. Pic is from Summer 2009, from Google Streetview. This is the south side.

Some notes on the design:

1. We aren't architects.

2. Passive house requires volume to surface area ratios be favorable to energy conservation, so a simple, square-ish box meets the need. We had sketched a number of modern designs, but there were issues. The existing garage form is more traditional, and would have to be revised to relate to the modern design, and the height limitations are more restrictive to flat roofs (8m, instead of 8.8m to the mid-point of a sloped roof). A traditional gable is proving more spacious inside, works with the existing garage, and will relate to other houses on the street.

3. The square box is stretched in the east-west direction a little to increase the south facade, while the diminished north-south dimension means more of the light from south-facing glass (few, and very small north-facing windows are a strong need of efficient houses) will reach the back (north) side of the house.

4. The main floor is raised 3ft above grade to increase window areas to the basement, and make basement space more pleasant. This places pressure on the upper floors to keep ceiling heights modest and floor assemblies thinner. As shown, there is enough space for floors 12" thick, but just barely.

5. House dimensions are 41.5ft x 34.5ft, excluding porches, which are generally not included in lot coverage and setback calculations.

Fig 1: Site Plan

Fig 2: Viewing North-West

Fig 3: Viewing South-west

Well, here is an early version of a house design in which we've worked out a number of things, including main and 2nd floor plans, and exterior features to some degree such as windows. The exterior detailing is not really given attention yet, so there are little things to sort out. The house is tall (about 34ft or 10.5m) in this drawing, which means blending into the street-scene could be an issue, so the tall trees (12.5m oaks are shown) are intended to help in establishing context - However, the tree on the left in Fig 2 is right where a hydro-pole is, so there are issues. The curving drive is really sweet, in our minds. The lower 'shrubs' you see are 3m (12ft) tall and thick cedar hedges already existing on the site, as is the separate garage. The Revit model didn't have much available to make them look more realistic.

We intend to bury the electrical service to the house to get rid of that nasty wire running across the property.

Height is measured to the mid-point of the roof, from the crown of the road - there are two roads abutting the property in our case, so I've taken the highest point available from these.

The view shown is the south facade with the larger windows. the Passive House software was already applied to the model and there seems to be no problem with meeting the heat load and the annual energy requirements - but there is a little too much sun in summer, pushing 50% of sunny days over the 77degF comfort limit, but that is probably because I haven't entered all the shading factors as yet, not knowing the tree choices and locations.