House W, a 163 m² home completed in 2024 in Nakafurano, Hokkaido, was designed to generate more energy than it consumes. Florian Busch Architects says it produces almost twice its annual energy use. That figure is the architects’ reported comparison—not an independently verified result: the available coverage gives no annual generation or consumption totals in kWh.
How House W combines solar power and heating
The project was designed for a family moving from Tokyo to Nakafurano, on Hokkaido’s Furano Plateau. The family wanted a home independent from the local power grid that would generate at least as much energy as it used. The architects say the completed home exceeds that target, producing almost twice the energy it consumes over a year.
New Atlas reports that the roof and exterior incorporate 56 photovoltaic panels with a combined capacity of 23 kW, along with a battery array. The architect-provided project description calls the panels a “solar skin”: they form part of the building’s dark, hard exterior rather than being treated as an addition after the design was complete. The architects say the plateau’s open landscape suited solar harvesting, and that active and passive solar performance shaped the design from the beginning.
For heating and hot water, the project description says an on-site water source with a steady flow and temperature feeds a water-source heat pump. The system supplies underfloor heating and domestic hot water. The sources do not name the heat pump’s model, output or efficiency.
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How the barn-like shape manages seasonal sun
The house sits on the former site of a farmer’s barn, amid rice paddies, asparagus fields, irrigation channels and roads. The architects began with a compact barn-like volume, then split and rotated its parts. The resulting gap forms a glazed interstitial space oriented toward the surrounding landscape. It also serves as a route through the house and as part of its climate strategy.
Adjustable louvers in this space are intended to block direct sun in summer while allowing winter sunlight to enter. Openings and glazing also shape solar gain. Timber continues through the interior, creating a contrast with the dark exterior. Together, the form and shading measures make the building’s seasonal relationship to sunlight part of the design, alongside its photovoltaic system.
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What the “almost twice” claim does—and does not—establish
Florian Busch Architects’ project description, reproduced by ArchDaily, says that over an entire year House W produces almost twice the energy it consumes. New Atlas reports the panel count and capacity, but says it did not have figures for the home’s actual power use. Neither source provides annual generation and consumption totals, the monitoring period, battery capacity, or a detailed account of grid exchanges.
New Atlas describes the house as off-grid, but the available project description does not specify its grid connection behavior. Without the underlying figures and system details, the reported annual multiple cannot be independently checked or translated into a precise surplus, payback period or carbon saving. It is a project-specific claim, not a performance benchmark for other homes.
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Why the design is not a plug-in template
House W’s energy approach depends on several elements working together: a solar-integrated exterior, seasonal shading, a water-source heat pump and a site with a suitable water resource. The project credits list Jan Warzecha for the integrated energy concept and Clenergy Japan for photovoltaics. The sources do not establish that the same balance would be achievable on another site, or provide enough measured data to compare the house quantitatively with other homes.
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- System Components：Delivers up to 10kW power output with 120V/240V single-phase split-phase support, making it suitable for smoothly running common household appliances. The system includes 18 × 590W solar panels with a total PV capacity of 10620W, capable of generating up to 39.36 kWh per day under optimal conditions, along with two 48V 314Ah portable LiFePO₄ battery offering 32.2 kWh of energy storage. Complete with necessary cables, this all-in-one solar solution is designed for convenient setup and reliable home power support.
- Upgraded Integrated Battery：ECO-WORTHY 48V 314Ah lithium battery combines advanced safety, high capacity, and smart system compatibility. It features a PACE 200A Battery Management System with multi-layer protection and dual breakers for reliable circuit safety. With a 16.076 kWh energy capacity and support for up to 15 units in parallel (up to 241 kWh), it delivers scalable and dependable power. A 7-inch full-color display, along with Bluetooth, Wi-Fi, and PC connectivity, enables convenient real-time monitoring. Designed to work seamlessly with mainstream inverters via RS485 and CAN communication, the battery also includes built-in wheels and handles for easy installation and mobility.
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