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Green Home of the Year: Energy-Efficient Compact House

Above-and-beyond energy saving features in this cost-effective New Zealand home won over Green Home of the Year judges.

HOTY-2021-logos_Grand Overall WinnerSometimes, small things can lead to a bigger one. That’s the case for the Emay Crescent Home in Pahi, Northland, New Zealand, which is the Grand Winner of Green Builder’s 2021 Green Home of the Year competition.

The four-person family home, designed by architect Duncan Firth, founder of Solarei Limited, and constructed by Grant Eager, director of Brogan Builders Limited, is a mere 785 square feet. It appears even smaller, thanks to its location on a very steep, west-facing 22,388-square-foot site. 

Optimal Efficiency Featured

According to homeowner Margriet Geesink, building a tiny sustainably focused home was an effort to keep things affordable, avoid a big mortgage, and attain a more flexible lifestyle.

From the Judges:

“Excellent use of space for a family of four. Great design and passive strategies blend into the natural environment and take advantage of amazing scenery.”

“Sustainable” and “solar” are two key words. Emay Crescent Home was designed as a vernacular-inspired model that incorporates traditional New Zealand materials, site-specific environmental design principles, passive solar gain with ample winter sunlight, and a sensitive westerly orientation, which optimizes harbor views while reducing solar gain. The home design also maximizes air flow and promotes outdoor living.

The floor plan is orientated on an east-to-west axis to achieve economy of construction, practical vehicle access, outdoor living, and optimization of westerly views. A 200-square-foot loft space over bedrooms creates more livable space.

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Optimal Efficiency view from deckA north-facing veranda roof brings low-angled winter sunlight into the front aspect of the home during winter and also provides shade to the outdoor living area during summer. The roof veranda opening is specifically designed to achieve winter sunlight and summer shading. Living spaces also receive direct passive solar gain with westerly outlooks over the neighboring Kaipara Harbour.

During summer the home is designed for optimized passive cooling using stack effect (hot air rising principle) and cross ventilation. Windows are specifically positioned to maximize passive air flow and cooling, reducing heat buildup from westerly afternoon solar gain.

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The house is designed for an anticipated electrical energy load of 1,500-2,000 kWh annually or an annual energy index of approximately 24.5kWh per square meter. Internal temperatures passively peak at 24 degrees Celsius during later afternoon mid-winter, with the extreme low being 17 degrees Celsius during the early morning. 

Green technologies and features which have been used for this home include off-site prefabrication, structurally insulated panels in the walls, metal-insulated panels in the roof, and above code insulation for floor, walls, and ceiling. There is also New Zealand-made metal cladding, Canadian cedar fascia boards at roof edges, and a timber subfloor clad in a 10mm recycled native hardwood called “kauri”.

Indoors, you’ll find argon gas insulated glass, energy-efficient appliances, water-efficient taps in the bathroom and kitchen, and breathable bio-paints for interior finishes. Living spaces receive direct passive solar gain with westerly outlooks over the Kaipara Harbour.

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In terms of irrigation and moisture management, there is an onsite tiger worm composting system that treats black and grey water (Geesink notes that it was “time to get some new pets” — worms for the waste tanks), a hot water heat pump that sucks heat out of the air, and capacity for 10,000 gallons of rainwater harvesting and fire water storage.

A limestone chip driveway aids with irrigation efforts. “Our land is very muddy and sticky,” Geesink notes. “Limestone chip is the material of the land, and it comes from a quarry not far away. The water can easily drain, and the lighter color matches the landscape and beach area around us.”

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The bottom line: The combination of standardized construction methods, site-specific environmental design, passive solar gain, passive cooling, energy-efficient technologies, and building technology create a small, desirable, sustainable family home.

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  1. The Emay Crescent Home’s doors and windows feature highly efficient Rylock glass, designed to reduce excess sunlight and withhold heat when desired.
  2. Decks are all-wood, locally sourced New Zealand Pinus radiata timber.
  3. Interior floors are made of New Zealand natural hardwood and recycled kauri flooring.
  4. The Knauf Insulation-lined walls include a thick composite of polyester and recycled plastic, which offers thermal performance and sound control.

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The home is orientated on an east-to-west axis to achieve economy of construction, practical vehicle access, outdoor living, and optimization of westerly views. Credit: Margriet Geesink

Project Stats

Name: Emay Crescent House, Kaipara District, Northland, New Zealand

Builder: Grant Eager, Brogan Builders Limited

Architect/Designer: Duncan Firth, Solarei Limited, Architect

Photographer: Margriet Geesink

Key Components

Appliances: IKEA kitchen and pantry bay; Fisher & Paykel energy-efficient refrigerator, oven, induction hob and washing machine; Mitsubishi energy-efficient microwave

Automotive: Schneider Electric PDL electric charger

Building Envelope: Formance walls (165mm R 5.7 structurally insulated panels—SIPs); Metalcraft roof 215mm R 5.3 metal insulated panels (MIPs); inside walls (10mm gypsum board, 8mm poplar plywood)

Cabinets, Shelves, Millwork: 20mm New Zealand pine plywood; 18mm particle board shelves with smooth acrylic spray paint finish

Caulks and Sealants: Sika caulks and sealants

Countertops: IKEA Corian 

Decks: 20mm-by-90mm New Zealand Pinus radiata timber frame

Doors and Hardware: Rylock glass exterior doors; hollow core Pinus radiata doors with 8mm medium density board, smooth spray paint finish; Halliday Baillie chrome finished hardware

Electrical: Schneider Electric fixtures and fittings

Exterior finishes: Metalcraft cladding (T-Rib, 5 Rib trapezoidal metal roofing profile); fascia (310-by-20mm Canadian cedar); soffit (6mm villa board); James Hardie smooth plaster finish 

Fire Protection: Metalcraft cladding (T-Rib, 5 Rib trapezoidal metal roofing profile); 3,300 gallons of firefighting water

Flooring: 10mm New Zealand natural hardwood recycled kauri flooring

Insulation: Knauf Insulation in walls (140mm R 3.2 composite polyester and recycled plastic); Climafoam subfloor (75mm R 2.8 closed cell polystyrene)

Landscaping: Native tree restoration plan; vegetable garden

Lighting: LED or energy-efficient lighting throughout 

Paints and Stains: Resene Paints (low VOC, environmental choice, made in New Zealand)

Plumbing/Plumbing Fixtures: PVC plumbing

Roof: Precision Roofing (metal insulated roof panel); Metalcraft T-Rib, 5 Rib trapezoidal roofing profile 

Telecommunications: Standard/local connection

Ventilation: Natural ventilation

Water Filtration: Puretec Hybrid-R

Water Heating: Aquarian 275L heat pump

Water Management (indoor/outdoor): Stormwater to public line

Window Coverings: Roller blinds polyester with a layer of PVC

Other:  Water flow, natural sewage water system. Natural waste system treats sewage; black and gray water are separated. Black water (sewage) is treated using a natural wormarator system (tiger worms), which naturally digest human waste. Gray water is irrigated over site.