Sustainability at Kotare
the buildings
We constructed this guest facility in 2021 with an aim to minimising environmental footprint in construction and in use. It was architect-designed by Buck Associates of Christchurch, the team who'd worked with us in 2007 on stage one of the house, which won Henderson Building (Timaru) a Master Builders' Regional Gold Award for Sustainability.
Both parts of our house use durable, energy efficient and low-maintenance materials, including:
• Strong concrete poured on-site for the reinforced and insulated foundations uses Holcim Duracem slag (a steel-making waste product) to reduce the total amount of high-carbon emission cement required. • Interior earth/lime plaster coating on the heat-store concrete block wall, a breathable self-coloured natural material. Outside, the durable grey decking is made from a recycled plastic and rice hull composite which does not require staining.• Magnum board interior linings, were chosen as a lower-carbon alternative to gypsum/cement boards. • Terralana insulation, made in Christchurch from NZ wool; in addition to some specialist extruded polystyrene ceiling and underfloor insulation panels.• Exterior ‘Vulcan’ charred pine cladding from Abodo, which requires oiling but not painting. • ‘No-paint’ oak appearance German-made PVC window frames from NK of Christchurch, supporting double glazed, argon-gas filled and low heat-emission coated glass. The bathroom window is triple glazed. They are a European-style two-way opening (hopper tilt or side-turn) design. Glazing is minimised on the colder south side except within the courtyard, where a large recycled NK French window provides guests with summer sunset views without draughts.
• Clearstory windows, high in the rooms, provide natural ventilation and extra daylight from the north.
• Stage one platform was cut into the clay hillside at the East in 2007 which allows the landscape to extend over the waterproofed concrete as a ‘green roof’. Stage two has a more conventional timber frame construction and a Coloursteel roof. Both have some Oamaru quarried limestone external cladding, to help link the designs and to reduce use of concrete.
• For a magazine article and photos about stage one of the house, see this link to NZ Lifestyle Block .
the technology
• Tiled non-slip floors are well lit by glazing from the north side for passive solar gain; with water pipe circulation installed beneath – this water is heated by an air to water heat pump from Warmth NZ. (Heating by heat pump is 2.5 x more energy-efficient than using the same power directly in radiators.) • Shower head is a water-saving yet satisfying aerated Satinjet Koha from Methven of NZ. • Waste water is treated entirely on site, using a two chamber septic tank, filters, a treatment wetland with planted sedges, holding tank, pump and dripper lines within trees.• The photo-voltaic (PV) electricity generation on site is grid connected. It was installed by Auric Energy of Ashburton who also run our electricity retailer Plains Power and pay us for the exported power. Our electricity generation exceeds energy use in mid-summer but we still import power during winter days. Carbon offsetting has been purchased for the net electric power bought (plus woodstove timber fuel in winter for your hosts' part of the house and an allowance for methane impact of our small waste volume disposed to Timaru landfill): totalling one tonne of CO2 equivalent per year, offset via EKOS carbon credits.• The first stage of the house also has a thermal solar water heater from Thermocell of Christchurch and a winter ventilation air-heater with automatic PV powered fan (a working prototype, designed by our architect).
• High north-facing windows also help with natural ventilation and the guest bathroom has an extract fan and heated towel rail installed.
the interior & garden
• Wood from sustainably managed forests and natural fabrics plus durable steel has been selected where possible in furnishings. Interior woodwork has been stained using oils from Natural Paint of Nelson and the walls are emulsion painted using Resene Environmental Choice water-based products. • Bedding, towels and dishcloths selected from natural cotton (see Better Cotton Initiative ) or cellulose–derived fibres such as Tencel. Our superking size winter-weight duvet is duck-down filled. Polyester generally avoided, as a source of microplastic pollution. And the inside doormat was made from recycled car tyres and plastic bottles!• Many of the books and DVDs in the fascinating guest library have been acquired second hand, over our lifetime. The subjects are eclectic… When did you last sleep in a library? • Single use item packaging is mostly avoided – so no soap wrappers or small liquid pottles and larger refillable ones are preferred. EcoStore products favoured, for ‘no nasty chemicals’ and we choose them unscented. We also use Fletchers, a local artisan soap maker, for small colourful scented soaps, which we present in reusable screw-top jars. Paper for printing is from 60% wheat straw and 40% rectcled wood fibre.• Guest have choice of loose teas for a teapot as well as tea bags, home baking as well as Canterbury manufactured and packed items. Fresh coffee choices with a coffee plunger. Home grown fruit bowl in season.• We grow seedlings and plant out many native trees and shrubs each year on the edge of our Kotare QEII bush covenant. The bush restoration will provide a home for nature and also help to store carbon. Over 3Ha of growing bush now compensates for methane carbon emissions from our tenant’s 20 sheep grazing on the permanent grasses here. We also don’t use Urea fertiliser, preferring clover as a nitrogen fixer for pasture. • Our orchard is managed using organic principles and the fruit harvest is spray-free. We sell at the Farmers Market
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