House features and design:
This design is focusing on multiple possible uses depending on the family's lifestyle, growth of family and allow multiple changes to requirements.
The initial thought is around the use of the fantastic section, exposure to the sun, great level access to the property, expensive views and the fact that this view can never be built out (reserve). This ensures all bedrooms and living area have exposure to the north sun. Children bedrooms are equally important as the master bedroom, this is why ensuring perfect orientation was the key. Same time it was important to ensure privacy, with careful positioning of windows that enables views from the bed towards the hills but same time protects views from the street. All bedrooms enjoy a walk-in type wardrobe, with more than sufficient storage space, ensuring all can be used as bedrooms, not like many standard floor plans, where the third bedroom becomes storage altogether. In saying this, one of the three bedrooms can be turned into a games room, as all bedrooms have TV and hardwire data connection.
Ground floor hallway is a built-in kitchenette, that can also function as spacious laundry. Alternatively, there is another room called “storage” that has all the installation already prepared to be turned into a mud-room, separate laundry, extra toilet or even third small bathroom. Ensuring versatility and future proofing.
A most important factor in Vila design was performance and durability. With extensive building science knowledge from overseas, we were not satisfied with code-minimum standards and certainly not with conventional timber construction, that hasn’t been changed for “100+ years”
Construction system we selected is high performance, factory manufactured, structural insulated panel, SIP. This specific SIP is exactly the system proved to be the most successfully applied SIP in North America, Europe, and Japan and tested and Codemark certified for compliance with NZ building code.
The walls and roof are completely thermally broken, and super insulated with R-value of:
But most importantly very air-tight to withstands occasional strong winds.
Foundation is concrete slab with insulation under the slab and thermally broken concrete edge. Installed is also hydronic in-slab heating with water heated using European type air-to-water heat pump, heating domestic water and same time also in-slab water. Radiant heat from underfloor heating doesn’t function by moving air. Unlike standard heat-pumps it heats the space in a similar way as sun, radiating the heat from ground up, with 'warm feet and cool head', this is proven to be the most pleasant way of heating, and due to extreme level of insulation, proven to also be the most economical way of heating, heating all rooms throughout the house, evenly.
Solar gain through the windows is absorbed by exposed polished concrete and basically passively heating also domestic hot-water. And by running the water in the slab it distributes heated water to less exposed parts of the slab and equalizing the heat through the house.
The roof is designed with large overhang on the north side, which completely protects from the hot summer sun, but enables weaker winter sun to still light all corners of the rooms. By opening a narrow window in the office on the ground floor and high window in the dining room in the upper floor, natural convection creates passive ventilation, which has been found sufficient even on most summer days.
Installation for air-conditioning wall unit has been put in place in upper floor above the storage units in living room, but so far it wasn't required. Most importantly, if required, all installation is already nicely hidden and cooling unit can be installed quickly, without visual obstructions.
An important aspect of house performance is also in terms of internal moisture control. Well insulated houses that are not air-tight cause significant issues to the durability of the structure. Vapour entering the wall not only causes potential rot on structural timber but is also absorbed by standard glass-wool insulation, which becomes heavier and sags, creating non-insulated gaps inside the wall.
SIP, on the other hand, is vapor-closed and air-tight and does not let any moisture in any form entering the inside of the wall, which results in better thermal performance and much longer durability (100+ years).
Another strong benefit of SIP panels is the structure. Double braced, factory laminated panel is incomparably stronger than conventional timber construction. SIP panels are used even on multi-story buildings and have also been tested on the largest EQ testing in Japan. Vila is on many aspects over-engineered, resulting in earthquake proofed structure.
Cladding on Vila is AAC (autoclaved aerated concrete panels) from specialised.co.nz. This cladding system is an additional layer of thermal insulation, sound insulation, completely waterproofed, and on 20mm drained cavity. All flashing systems have been designed above the code minimum, for very high wind zone, resulting in longer coverings over critical junctions (barge, eave, soffit, parapet, apron etc).
Outdoor landscaping and deck
On the north side landscaping design creates two large platforms, terraces, plenty of space for entertainment. It is designed to be easy care with clear access. There is space for large BBQ party, enough flat area for a trampoline or a veggie garden. This home is easy to enjoy, with very little time required to keep it tidy.
Upper floor deck is facing west, protected from Easterly winds and soaking in all the sunshine until the sunset, allowing even many winter days to be spent outside. Composite decking not only creates a level access, but it also doesn't require any maintenance.
Lifestyle, Comfort and Running Cost
As homeowners for the last 2 years, we experienced some of the most comfortable living in NZ so far. It reminds us of the lifestyle we were able to have in Europe, where we still only wear t-shirts inside our homes, in the middle of winter. We often don't even know what temperature is outside because we are so well protected from the external environment.
In saying this we calculated it costs us only about $80 a month to heat the whole house to comfortable temperatures all day long, for the whole winter. We don't even turn the heating on and off, it works automatically. But equally, by using passive ventilation and due to large overhangs on the north side, we don't feel hot in summer. We were happily relying on passive ventilation, and have not required air-conditioning.
On most sunny winter days, we enjoy upper floor deck, well protected from prevailing easterly wind. Leaving the stacker slider completely open and enjoying the winter sun until the very last sun rays before sunset. After sunset, using dimmers on most lights, we can create a nice atmosphere inside, while still being able to enjoy the beautiful view of the night city lights. From the living room, bedroom and even from the bath in the main bathroom. By turning external lights on in the master bedroom balcony, you maintain privacy in the bathroom and enjoy the view at the same time.