The Cape Pt 8: Straithouse is complete!

With the build complete, here’s the final reveal.

2021-02-18

By Richard Keech

OK, here it is.   We moved in nearly two weeks ago.  It’s every bit as good as we’d hoped.  Too early to know much about how the house performs from an energy point of view, but initial indications are promising.

 

Photo Gallery

 

 

 

Key features

NatHERS rating Design rating 8.3.  As-built rating 8.7 stars
Certification Passive House classic
Areas Indoor: 132m2 ; Roof: 235.6m2;  Garage: 31.8m2
Configuration 3 bedrooms, split-level
Construction Timber floor on stumps, 140mm stud-frame.
Cladding Reverse board and batten with radial-sawn timber
Glazing Triple-glazed, timber-framed
Hot water 160L internal tank, CO2 heat-pump, 5L/min shower heads
Heating/cooling Two small split systems
PV Panels: 22x330W Trina Honey = 7.3 kW

Inverter: Fronius Gen24 Plus Symo 6.0 (hybrid, 3-phase)

Other Green roof on garage,

Colorbond, corrugated roof (colour: Surfmist)
Underground rainwater tank (10kL)

Building energy efficiency

Ceiling insulation R6 glasswool batts
Wall insulation R4 glasswool batts. Augmented with 25mm XPS where required to minimize thermal bridges.
Floor insulation R5 glasswool batts enclosed between vapour-permeable layer and floor sheeting.
Glazing units Low-e, argon-filled, triple-glazed with warm-edge spacers.  Ug values from 0.58 to 0.67
Window frames / mechanism Painted, finger-jointed pine frames with powder-coated aluminium face. Mix of 68mm and 88mm frame thickness.  Mix of fixed windows, tilt-and-turn, sliding door, hinged doors.
Glazing performance Average window U value (Uw) of 0.79.

Average window solar heat gain of 0.44.

Passive House features

Vapour-permeable layer Solitex Extasana (walls and subfloor) and
Solitex Mento Plus (roof), by Proclima
Air-tight layer Intello by Proclima
Air-tightness 0.58 (ACH50) as tested at completion
Heat Recovery Ventilation Stiebel Eltron LWZ170e Plus with FEQ air-quality sensor and additional outside-air filter box.

100-300m3/hour air-flow (13-250W power).

Design features

Roof Novel asymmetric gable with sloping ridge line. North: 34°; South: 17°. Supports excellent solar generation.  Eave extensions on east and west provide generous shading.  Exterior north wall fully shaded in summer by careful eave configuration.
Posts 200mm Cypress posts hold down the eave extensions and provide a dramatic visual feature.
Posture The floor structure is raised and cantilevered around the perimeter, giving the house a slightly elevated, crouching posture.
Glazing config The glazing across the north side takes the form of a ribbon window, with black panels completing the cladding in the sections between the windows to round out the ribbon effect.
Vaulted ceiling The main living/kitchen area has a vaulted ceiling using ply sheets with expressed joints and subtle whitewash finish.
Split-level The single story is split across three levels to follow the slope of the land. This means the interior sill height for the north glazing changes with each of the three levels, as part of the ribbon window arrangement.
Garage recessed The garage is separate from the home and dug into the slope.  This makes its roof low enough to open up sight lines from the elevated east end of the house, over the top of the garage.

 

heating and cooling

Split systems Two-port 5.2kW inverter multi-split system from Mitsubishi Electric (MXZ-2F52VF-A1), with two 2.5kW internal units (MSZ-AP25VGD)
CoP of 3.8 (heating), 3.7 (cooling).
Fans – Bed 2,3 Haiku L, 52”, from Big Ass Fans. Hybrid resin blades.
Fans – Bed 1, Living Haiku H, 60”, from Big Ass Fans. Bamboo blades.

 

Appliances and lighting

Feature downlights Brightgreen SHX Curve
(mix of 550, 900 and 2000 lumen).
Cooktop Miele 80cm induction with downdraught, recirculating extraction and carbon filter.

Model KMDA7774FL.

Materials & finishes

Cladding Radial-sawn silver-top ash from Radial Timber Sales.  BAL 29.  Class 2 durability.
Floor boards Tasmanian Oak
Tiles Feature tiles: Make: Inax; Style: Yohen Border

Floor tiles: Make: Fiandre: Style: Fjord White

Paints / Stains Internal walls: Low VoC.

Floor boards:

Ply ceiling:

Posts:  Cutek Extreme

 

Shading control

Exterior Motorised zip blinds fitted into façade over east (sliding door and one window) and west (one window). Zipner units provided by Logikhaus
Interior Cellular blinds by Nordic Blinds on most glazing.  Top-up-bottom-down configuration allows flexible control over shading and privacy

 

Water-saving features

Shower heads Methven Kiri Satinjet ultra-low flow (5L/min)
Tank 10kL underground tank with rainwater harvesting

 

Credits

Designer

Luke Middleton – EME Design www.emedesign.com.au

Builder

Dave Martin – Martin Builders www.martinbuilders.com.au

Green roof

John Hassell – Greenly www.greenly.com.au

Glazing

Logikhaus www.logikhaus.com.au

Blinds

Nordic Blinds www.nordicblinds.com.au

Air conditioning

Mitsubishi Electric www.mitsubishielectric.com.au

Heat recovery

Stiebel Eltron www.stiebel.com.au

Hot water

Reclaim Energy www.reclaimenergy.com.au

Solar panels

Trina www.trinasolar.com

Inverter

Fronius www.fronius.com/en