Wanaka Energy Efficient SIPS House

We are well underway with the structure of a new energy-efficient family home at 52 Dale Street in Albertown. The house is for a typical Wanaka family of 4 with all the associated equipment that comes with a love of the outdoors whether this is at home, around Wanaka or further afield. The house plan accounts for changing needs of teenagers, allowing some independence but also keeping the family unit close-knit and allowing to accommodate family and friends.

The site is the last vacant site in the original stage of Riverside Park so the house had to take into account the position of the surrounding residences in order to create outdoor spaces, avoid overlooking, utilising the sun and making the most of selected view-shafts. Knowledge of how the clients live in their existing Alberttown residence has been utilised to create an outdoor courtyard area that captures the summer sun from mid-morning to late afternoon while sheltering from the typical North-West summer breeze. Alternative outdoor areas (or ‘rooms’) are created to the North and East, vege gardens to the West and the business end vehicle and services areas to the South.

Floor Plan of Proposed Residence

The clients currently live in a 1970’s crib (Holiday Home) that was renovated 6 years ago, receiving a full interior fit out with new internal finishes fixtures and joinery, and as much insulation as possible, so they are fully aware of the benefits of improved thermal performance. However there are limitations on how far you can thermally improve 40 year old construction, so the decision was made to start fresh and employ the best and most current thinking in thermal efficiency. The principles of Passivhaus construction have been employed but only to the extent that readily available materials and construction techniques have been utilised. The construction contract for the house went out to tender to several home group companies and to builders that were familiar and passionate about energy efficiency and eco-friendly construction.

The Tender was won by a local building company Kia Kaha run by Scott Pickett who priced competitively and also provided some good alternative options on construction and materials. The house was detailed with 150×50 timber framing that was sheathed with plywood RAB for airtightness and bracing, and with a horizontal 45×45 structural batten to support the cladding and to eliminate the need for noggins (dwangs) this reducing the amount of thermal bridging through the structure. Internally the 150×50 framing was wrapped in Intello which is an airtight vapour control membrane, and also with another 45 x 45 horizontal batten allowing for a services cavity to minimise penetrations through the vapour control membrane and allow an uninterrupted layer of insulation. A further layer of 50mm insulation was run between these internal battens to reduce thermal bridging further. Scott from Kia Kaha Developments proposed an alternative wall construction using Structural Insulated Panels (SIPS) that would not only improve the insulation value of the wall by reducing thermal bridging but saved $15,000 on the cost of construction. Scott has built about seven SIPs houses in the South Island, including New Zealand’s first SIPs house in Alberttown (less than 100m from Dale Street) so is not only a leader in this technology but has good experience in its construction. The SIPs panels used are Kingspan TEK panels that are imported from the UK. There are some NZ based alternatives arriving on the market but currently, the Kingspan panels are superior and cheaper, with a 110mm Urethane core sheathed both sides with 15mm Type3 OSB (Oriented Strand Board). This marine grade OSB is absolutely formaldehyde-free, glued by PMDI resin and provides all the required bracing and forms an airtight barrier.

I will enter further detailed posts on the use of the SIPs panels on this project as well as other elements of the design that are being utilised to create a comfortable energy efficient home that is far superior to current building practices.


Wanaka Haven Luxury Lodge

This design for a combined residential property and 5-bed visitor accommodation was challenging despite having a large 4-hectare site. The dedicated platform was relatively small, poorly orientated and came with a 5-metre height restriction. A number of configurations were considered before settling on separate wings of private and guest accommodation that are joined by the living areas facing the North.

This gave priority of view and sunlight penetration to the guest bedrooms and both the guest and private living areas. The remaining Guest bedrooms face east and the private bedrooms face east through an internal courtyard.

The courtyard allows for breakout areas for both the private and guest areas away from the predominant Northwester and potential areas of shade in the summer months. Hedging will create outdoor rooms within the courtyard separating the entry from amenity spaces.

A limited combination of materials was used in the project with render and schist to Northern aspects receiving a lot of sun and wind, and natural timber (cedar, Douglas fir and Macrocarpa) to areas adjoining human activity and in shaded verandahs or Southern facing areas. This added warmth to the exterior while minimising maintenance.

The warmth of timber is carried into the interior with the use of double timber doors into the main entry and timber floors throughout the living and bedroom areas. Circulation areas are tiled and are generous in size to avoid damage from suitcases and bags. There is a drying room for ski gear to minimse gear inside the guest rooms.

 The 15 degree pitch allows the skillion ceilings to give a sense of spaciousness without feeling too lofty and keeping the building within the height restriction. A minimum 2.7m stud was employed to maintain a sense of space and ensure that mountain tops were not cut out of view.

The total floor area of the project is 560m2 so energy costs were a key consideration. It was decided that the guest and private living areas would have a wood-burner each for visual comfort and any power outages but the remainder of the heating would be meet with a geothermal (ground to water) heat exchanger that runs under-floor heating (UFH) throughout the house. This simplified the heating and domestic hot water systems providing low maintenance and highly efficient use of energy.

To keep heat loss to a minimum the perimeter included 600mm deep polystyrene block foundation walls and continuous XPS insulation under the slab.

The walls received a 100mm layer of batt insulation between 150mm studs and 100mm noggins and a second layer of 50mm rigid insulation continuous over the noggins. The ceiling received similar treatment with 200mm batts between the rafters and 50mm rigid insulation between the purlins on edge. This criss-cross of insulation minimizes cold bridging through the structure.

To stabilize internal temperatures and to provide good acoustic privacy between the rooms, 140mm masonry block work was used internally to enclose all bedrooms and living areas.

The use of PVC windows from NK Windows in Christchurch added to the thermal efficiency of the enclosure and allowed flexibility with tilt/turn or tilt/slide functionality.

All bathrooms were treated as wet rooms and finished with quality Grohe and Villeroy and Boch sanitaryware.

Each guest room has its own external sitting area that creates a private zone while providing shade from the summer sun while allowing the low winter sun to penetrate into the rooms.

As a rural site on site septic disposal was required. Two Biolytix Biopods were utilised using worms and other organisms to convert sewage into garden irrigation water. The driplines where designed to irrigate the lawn directly to the North of the building while making allowance for a future swimming pool and spa pool. Both of these shall be heated using the existing geothermal heat exchanger.

The clients are busy establishing productive planting on site with an orchard already providing fresh berries for the guests. It will be interesting to see the landscaping grow and further define spaces extending beyond the house.

Photography : Larsson Photography and Chris Norman Architecture Ltd.

Queensbury Hills House: Project Update

The Queensberry Hills house is now under construction and first impressions are more than we had wished for. As a stand-alone object in the environment it feels well connected to the landscape with the precast concrete panels similar in tone to the local rock outcrops. The decision was made to eliminate the cantilevered walls on the downslope side of the house in order for the house to rise out of the ground while simplifying load paths due earthquake loading in combination with the high snow loading found at the 560 metre elevation. To minimize earthquake loads we have also decided to use a schist chip wearing-layer over the membrane roofing in lieu of the tussock & earth covered roof.

The robustness of the panel walls is symbolic that the house is designed for a windspeed of 216km/ hour which will lift grit to effectively sandblast the exterior. The openings in the panels now frame particular viewpoints which were previously lost in the immense landscape panorama. There is particular focus on features like the Clutha River, Lake Hawea, the Saint Bathans and Pisa mountain ranges.

Oversized conduits have been passed under the walls allowing for flexibility of services and heating options. The primary heat source is a ‘Earth Tube’ ground to air heat exchanger which will feed into a high spec Energy Recovery ‘Air to Air’ heat exchanger.  The Earth Tube comprises of a 225mm diameter corrugated pipe that is run through a 140 metre long service trench from the site boundary. It is estimated that if the outside temperature is -5o C and the ground temperature is at 10oC we should be able to deliver the air at 7oC to the house.  This incoming air will then pass through a Counter Flow Energy Recovery Heat exchanger that will be preheated by the transfer of energy from the stale exhaust air that is to be vented to the outside. Modern ERV systems such as the Zehnder Comfosystem that is being offered by Fantech in NZ offer up to 95% heat recovery of the exhaust air. As a physical feature the client is looking at a sculptural Cheminee woodburner that will be direct vented to avoid drawing preheated fresh air up the chimney.

Given the large area of the site the client is still considering a ground loop ‘Ground to Water’ heat exchanger to heat the domestic hot water. We originally considered this as a heat source for under-floor heating but we are moving away from the idea of this given the high level of insulation air tightness and efficiency of Energy Recovery ventilation systems. In simplifying the heating system the floor slab may provide potential for thermal mass and temperature stabilization through the employment of Phase Change Materials being incorporated into the slab. This technology is relatively new and may be difficult to source products for the floor within NZ.  This technology is available as a proprietary product in Germany with Doerken offering a product called Delta Cool 24 which is available as a panel product with 20mm of Delta Cool 24 offering the equivalent heat capacity storage as 240mm of concrete.

The project has been designed so that it will be constructed as a weathertight structure with a free spanning roof structure allowing the interiors and services to be completed in a manner similar to a commercial fitout. The advantage of this is that the client can confirm the interior layout within a physical space, adjustments to the fit-out budget can be made after monitoring the ‘lock-in’ costs and the design can respond to changes in technology and product availability in the time it takes to get the necessary building consents and to construct the building enclosure.

If the Italians had colonised Wanaka

I read in the Otago Daily Times that the Upper Clutha Environmental Society are appealing against a residential platform in Dublin Bay proposed by Annabel Langbein and Ted Hewetson.  While I applaud the efforts made by the Society to provide a check against unbridled development across the region, I do question the impact on amenity that this residence will have as there is already existing residential development and human activity is clearly etched into the landscape.  Personally I think Dublin Bay would be a great spot for further intensification into a compact village that enjoys the lakeside amenity while having little impact from other positions either around or on the Lake.

This raises the question ‘have we got the District Plan and Wanaka Structure Plan correct?’ The Structure Plan clearly defines Wanaka’s urban spread within the confines of the Clutha and Cardrona Rivers down to Hill End and up to Rippon. Any land outside of this area is zoned Rural, however residential activity in the guise of Lifestyle blocks is already peppering this landscape in a similar way that has occurred in the Wakatipu Basin. I doubt that either the Wakatipu or Upper Clutha basins will provide more than minor agricultural benefit to our communities within the next 20 years, a great loss of rich productive land.

If the Italians had settled the area they would not have allowed this to happen! They would cluster their urban centres around transport hubs such as rivers and lakes providing potable water and additional food source as well as providing amenity for social and leisure activities. Alternatively they would have settled on the foothills of the mountains, either way the land outside of these localised communities would remain productive.

A good example of this can be seen in the foothills of the Italian Alps around Lake Garda where the lake edge is dotted with clusters of communities that neither detract from the amenity of the lake nor the surrounding mountains. Other great examples can be seen throughout the coastline of Croatia, with fantastic dense communities such as Hvar and Korcula providing a beautiful social hub on the water edge and you only have to walk less than 5 minutes and you are in productive rural areas.

Lakes Wanaka and Hawea present many opportunities for clusters of communities around the waters edge that are visually separated from each other leaving a sense of openness within an natural landscape. If we intensified the original communities of Lake Hawea; Johns Creek; Hawea Flat; Alberttown; Lake Wanaka and Tarras along with new intensified communities at Dublin Bay, Glendu Bay and dare I say it Damper Bay, we could all enjoy the Lakes and Rivers, utilise the productive flat land while enjoying the rural amenity instead of living in a suburban blanket of individual landlocked plots.

If we all had a lake view and access to the waters edge within 5 minutes walk would we need to have a quarter acre private realm with green grass that requires mowing and irrigation?


The much used term ‘Sustainability’ has been a great driver for awareness of the resource and environmental issues that face current and future generations but I believe its misuse or overuse is starting to dilute not only what is possible but what we should all be doing.  Technically architecture (as we know it) is not a sustainable activity unless we can utilize renewable resources from within our  ‘fair earth share’ of ecological footprint, currently about 1.7 hectares per person on earth (see NZ Footprint project by Otago Polytechnic Centre for Sustainability).

This may be an impossible task but we need to seriously review how we build particularly in terms of embodied energy of materials, size of building for purpose, durability and adaptability. Sticking a solar panel on your house or marketing your existing building products under the label of ‘Future Proof Building’ does not make you sustainable.

For example; in the Houses (NZ) Winter 2011 magazine there is a feature on a new contemporary residence with a designers note that ‘’ Sustainability was also important, and the house utilizes solar hot water and rainwater recycling’’.  These are great things to do but this is for a single bedroom 200m2 house with full height glazing to about 70% of the exterior walls with air conditioning as a heat source.

Also the designers behind the new Wanaka Lakes Health Centre claim ‘sustainable design was a key consideration with approved green build materials and energy efficient services design…’  Sustainability doesn’t come into my mind when I view that the new building in effect is a large shed with a very deep floor plate (30 x 54 metres?) that relies on mechanical services and light .  There was so much scope to employ natural ventilation and lighting rather than rely on ‘energy efficient’ mechanical services; the costs in allowing openings within the plan would offset the costs for increasing the size of services to create an artificial environment and would have greatly reduced the running costs over the life of the building.

So the Sustainable banner comes out again and again but I think we need to try a little harder than this if we truly want to work within our limited resources whilst creating architecture that truely delights.

Hill House

A precast concrete panel house designed to withstand a harsh sub alpine environment while making the most of passive solar gain and ventilation.


Tried and Tested

After formally studying architectural history for many years and constantly reading books on architecture, it is great to come across architects that I have not heard of, architects who have not made the mainstream but have a body of work that is quite inspirational and refreshing.

Recently I stumbled across the work of British born Laurie Baker (1917-2007), who practiced during the height of modernism but found his own path and produced contextural organic and energy efficient architecture.

Although he was a humanitarian living and working in India, he produced a set of ‘Architectural Principals’ that strikes accord with many of the methods and principals that I like to apply within my own local context. Below I have attached his Architectual Principals from a website dedicated to him and his work

While it is fantastic that the general public is developing an awareness of sustainability in architecture, it can be frustrating to see companies behind the greenwash promoting ”cutting edge” ideas and methodologies that have been tried and tested principals for some time. Finding Laurie Baker’s work demonstrates that sustainability has long been a part of good design, something that many architects throughout New Zealand and been achieving and tring to promote for some time.