The Ultimate Net-Zero Beach House: The Kiwi Bach
The Victoria University of Wellington designed and built a New Zealand weekend home for this year’s Solar Decathlon. Called ‘”First Light” and lovingly referred to a “Bach” – pronounced (batch), the home won the Engineering and Energy Balance contests and clenched a podium finish as 3rd overall. Not bad for their first Solar Decathlon effort.
At 800 sq. feet, the home has an air of relaxed unpretentious calm, with the self confidence of a well-designed and built home. The team also unveiled an innovative solar hydronic clothes drying cabinet that uses a fraction of the energy that a traditional clothing dryer uses, yet dries the clothes in a similar amount of time.
Active Solar Aspects
On the roof, a 6.3 kilowatt array comprised of 28 polycrystalline photovoltaic (PV) panels accompanies the 40 solar evacuated tubes that supply the home with solar based electricity and hot water.
Passive Solar Aspects
This home incorporated passive solar heating and cooling into its design.
The slats on the southern facing roof overhang and extension are angled and situated to block the summer sun, yet will allow the lower winter sun’s heat to be absorbed into the home.
Because the New Zealand team is from the Southern Hemisphere, often referred to as the area ‘Down Under’, within their location, a passive solar home would face the north in order to gain the maximum benefits from the sun for a passive and active solar building. (See the diagram below.)
The sumptuous wood that surrounds the Kiwi Bach was pressure-heat treated in a kiln, a process that strengthens, hardens and darkens the wood, and bypasses the need for any additional sealants or toxic finishes.
Upon entering the home, the living room features a prominent southern facing window that allows light into it.
A poured concrete floor is located directly in front of the windows so that its thermal mass can absorb the sun’s heat energy in the winter.
A material with thermal mass is one that has the potential to absorb heat energy through the day and slowly releases it through the cooler evening and night.
Creamy light yellow in color, the concrete is barely recognized as such, adds reflective light to the room, as well as the needed thermal mass to the passive solar equation.
Light colors for the floor, walls and furniture were placed near the source of light to reflect light toward the back of the home.
The map shows the earth divided between northern (shaded in yellow) and southern (white) hemispheres. If a passive solar home is built in the northern hemisphere, to receive the maximum amount of sun throughout the day, it would face the south. Because this home was being showcased in Washington D.C. for the Solar Decathlon, the windows and solar panels needed to face the south. If, however, the building is situated in the southern hemisphere, then the windows and solar panels would face the north. Luckily, this building is modular and can move to be situated either to face the north or south, depending on where it happens to be located, and this active solar house will still be optimally efficient – just as long as it is facing the sun.
The living room features a seating area with wooden panels that can be slid back to increase the room’s capacity for guests with comfortable space for extra seating / sleeping / lounging spaces.
The wooden panel slides to open or enclose and hide the upper area. Or, as I like to think of it, can be utilized to instantly clean the area.
In a smaller home, the utilization of space is important. Note that the cabinets under the seating area can be utilized as storage.
The team from New Zealand is the only Solar Decathlon team from the Southern Hemisphere to ever participate in the event.
Along with the challenges of designing and building a home in New Zealand, it was then disassembled, shipped across the Pacific Ocean, then reassembled for the competition in Washington D.C.
This was not a frivolous task, as high quality components: the pressure-kiln treated wood, gleaming concrete poured floors and kitchen table (see below), triple paned windows, along with a fully tiled bathroom, were used in the assembly of the home.
Strategic and integrated planning went into the design of the home. The team has many innovative features and passive strategies that could easily be overlooked.
Instead of using curtains that allow cold or hot air to easily go around the material, the shades for the window are guided by lines down the window to help with heat efficiency and insulation when it is desired.
I was testing out a panorama function with the new pan and scan mode.
The following picture shows the living room, kitchen and toward the bedroom areas. It’s a little over exposed near the kitchen area that was open to the north however, it gives an idea of a comprehensive layout. Additional photos of the home can be seen in the photo gallery below.
Elegant, rich, wood planks line the walls and ceiling.
The University of Wellington team utilized wool, a renewable and locally available resource, to insulate the structure. It also adds three times the R-value than is normally used in buildings.
A highlight in the kitchen is a large poured concrete table. The table can comfortably seat eight and also has storage space on its wooden sides.
The kitchen table was located under a skylight and not only adds a nice ambiance to dining, but it also can add warmth to the house as the table is made of thermal mass, a material that can store the sun’s heat energy.
If extra light or heat is not needed, shades built into the ceiling can be utilized to provide shade.
This year at the 2011 Solar Decathlon, concrete has been utilized in many of the houses to create poured concrete floors, book cases, sinks, and even entire houses.
The Hydronic Drying Cabinet
Just beyond the kitchen is a study area. It also serves a boundary function to nicely block off the main master bedroom and bathroom.
When going back around the study area, located to the side of bathroom, a innovative solar drying cabinet for clothes can be accessed.
After clothes are washed, water is first drawn out through a spinner, then can be hung to dry in the drying cabinet.
The hydronic drying cabinet uses the solar heated hot water as the energy source to dry the clothes. The drying cabinet is heated with energy stored in the hot water as it transfers the heat through a heat exchanger from the water to the air in the cabinet. As the clothing items dry, a fan draws the humid air out of the cabinet.
The drying cabinet dries clothes as quickly as a regular dryer but uses only a fraction of the energy. (Brilliant! I want one!)
The mechanical rooms for the home can be accessed from outside. The space doubles as a place for storage and maintenance.
Wellington University designed and built a home that is comfortable, efficient and elegant.
With the use of traditional materials such as wood, tile, concrete, along with its traditional look, its sophistication appeals to a wide market.
The home was estimated to cost $303,467 USD to build. While this house was created with a beach home in mind, because the inner space is well-designed, the house could comfortably house a couple or even a small family in any location.
This home is a medal winner, placing third overall.
This home has already been purchased and has been permanently installed in Waimarama, Hawkes Bay, New Zealand.
Click on a picture below to enter a slideshow of the photo gallery. Use the arrows to navigate or click on the right hand side of the photo to progress to the next one.
While on route to the podium, the New Zealand team took 1st in the categories of Engineering, Energy Balance (yes, it tested as a net-zero home) and Hot Water (the home solidly performs) and placed 2nd in Architecture. In order for a team to secure a medal standing, it also must place well in the rest of the points categories as the team from New Zealand did.
Fabulous job from the New Zealand team! See their video below for more scoop on the Bach.
See the original model from the University of Wellington
The University of Wellington’s Solar Decathlon Website: firstlighthouse.ac.nz
First Light’s YouTube Channel – Check out their time lapse builds
The 2011 Solar Decathlon Main Website: solardecathlon.gov