Super Energy Efficient Modern
Otter Bay
Another Super energy efficient home on Pender Island built using the Passive House method.
This was a fun project to work on. Really lovely clients that were open to exploring interesting ideas, with quality of build and materials and workmanship and of course, super energy efficiency.
Although this house has a relatively large floor area, the intent was not to be grandiose, but simply the desire to ensure that each space was big enough to function well. They have no intention of building again, so let's just do it right the first time. Room to move with materials, fixture and components that are good quality and built to last as well as each having their own spaces for hobbies.
This home was built to be energy efficient, but due to the shape of the house, the aspect ratio was quite high (the ratio of floor area to surface area) which in Passive House is a no no. The higher the ratio, the higher the heat loss relative to the floor area. This doesn't affect the comfort level in any way, but it does mean that we exceed the maximum space heating demand to achieve PH certification, which in this case was not the goal.
The curved roof structure was intended to soften the shape of the house and break up the linear mass, and yes, as a nod to the ocean just metres from the patio. The concrete retaining walls along the drive reflect both the roof and the undulating terrain they retain. By using the same rustic concrete embossed surface on the fireplace and kitchen island bar-back we establish continuity from some exterior elements and created an interesting and unique conversation piece.
Rain water is collected from about 25m² of roof area, and stored in a 166,000 litre concrete cistern under the garage. This system provides all the domestic water needs for an entire year. The gardens are supplied from a deep well which can also be called into service if the cistern runs dry. Weather patterns are shifting due to climate change so it was important to the client that they do their part to lessen the demand on the aquifer. The day may come when rain water collection won't be enough, but every bit helps.
A ground mounted 10Kw grid tied PV array helps to offset their annual electricity demand. Locating the array on the ground makes it easy to regularly inspect the panels and clean them to ensure they operate efficiently.
Details
Interior Floor Area (TFA) 297m² (3197ft²)
Heat Load = 14W/m²
Annual Space Heating Demand 20kWh/(m²a)
Walls U= 0.121 W/(m²K)
Roof U= 0.103 W/(m²K)
Floor U= 0.108 W/(m²K)
Windows (Triple Pane) Uᵂ= 0.77 W/(m²K)
Net Electric demand /a +/-3500 Kwh