Hangzhou’s Carbon-Negative Landmark: How Did This Old Building Achieve a 111% Carbon Reduction Rate Through BIPV?

Hangzhou’s  Carbon-Negative Landmark: How Did This Old Building Achieve a 111% Carbon Reduction Rate Through BIPV?

Next to Moganshan Road in Gongshu District, Hangzhou, a once-unremarkable 14-story office building is quietly undergoing a remarkable transformation. It is no longer just a building, but a vertical green energy station — the Hangzhou Digital Energy Port Incubation Building. With a total floor area of 9,642㎡, this reinforced concrete structure is demonstrating the future potential of urban renewal through photovoltaic curtain walls.

The incubation building was originally a conventional office building. Its low-carbon and energy-efficient transformation project has become a key demonstration project for Hangzhou in addressing the challenges of industrial park transformation in the new era. Before renovation, the building relied on a single energy structure, faced high renovation costs, and contributed little to the surrounding urban landscape.

In 2025, Zhejiang University of Technology Design Group took full responsibility for this major project, providing comprehensive technical support covering low-carbon planning, building energy-efficiency renovation design, and the development of an intelligent energy management platform. Based on the core concepts of “vertical energy generation, direct green power supply, smart operation, and upgraded appearance,” the project transformed the building into an “energy incubator” integrating energy innovation, industrial incubation, and a green urban image.

A Revolutionary Transformation of the Building Facade

The most remarkable part of the renovation was the revolutionary reconstruction of the building’s exterior facade, turning the building itself into a vertical green energy landmark.

With a total installed capacity of 263kW, the project is the first building in China featuring oversized cadmium telluride (CdTe) photovoltaic glass curtain walls covering all four facades.

The facade adopts 5D TECH Energy’s insulated CdTe power-generating glass structure, which improves the building’s thermal insulation performance. The specific structure is:

5HS + 1.52PVB + 3.2 CdTe + 1.52PVB + 5HS Double Silver Low-E + 12Ar Warm Edge + 6TP Ultra-Clear Glass

With a selected visible light transmittance of 40%, the photovoltaic glass achieves a balance between power generation efficiency, natural lighting, thermal insulation, and safety requirements.

A notable feature is that the CdTe photovoltaic glass used in this project incorporates 5D TECH Energy’s proprietary “Yicai (燚彩) Technology.”

This technology provides infrared reflection performance, targeting the main factor responsible for indoor heat gain — infrared radiation. In particular, it achieves up to 15% reflectivity for infrared wavelengths between 900–1500nm, further enhancing the building’s thermal insulation performance.

In addition, Yicai Technology minimizes the impact of color on photovoltaic conversion efficiency. While maintaining high power generation performance, it gives the light-blue transparent photovoltaic glass a modern and futuristic appearance, transforming the building facade from a cold “solar panel patchwork” into an attractive urban landscape.

Beyond Photovoltaic Facades: Building a Negative-Carbon Energy System

The photovoltaic curtain wall is only the starting point of the incubation building’s green transformation.

To achieve the goal of becoming a “zero-carbon” or even “carbon-negative” building, the Digital Energy Port industrial park integrates multiple advanced low-carbon technologies:

High-Performance Building Envelope

High-performance exterior walls and roofing systems significantly improve thermal insulation, reducing energy demand at the source.

Efficient Energy Systems

The project applies highly efficient ground-source heat pumps, dual-source heat pump systems, and fresh-air heat recovery systems to substantially reduce air-conditioning energy consumption.

Smart Energy Storage Management

A lithium iron phosphate (LFP) energy storage system is deployed as a key node of the “virtual power plant.” Based on electricity price signals and photovoltaic generation forecasts, the system intelligently manages charging and discharging strategies to achieve peak-valley electricity arbitrage and demand management.

Through the combined effect of these technologies, the park not only meets its own operational energy needs but also generates surplus energy.

Simulation results show that the annual carbon emission intensity of the Digital Energy Building is as low as -4.80 kg CO₂/m², achieving a carbon reduction rate of 111.13%.

This means that during its operational phase, the building has surpassed “zero carbon” and successfully entered the category of carbon-negative buildings.

Thanks to this outstanding performance, the project successfully passed the evaluation and received the “Zero Carbon Building” Design Stage Pre-Assessment Certification issued by the China Association of Building Energy Efficiency.

Unlocking the Potential of Existing Buildings Through BIPV

China is currently undergoing a profound transformation in its urban development model.

Statistics show that buildings older than 20 years across China exceed 70 billion square meters, while approximately 170,000 old urban residential communities require renovation.

Moving from large-scale demolition and reconstruction toward improving existing urban assets, urban renewal has become a new trillion-yuan investment opportunity:

· Residential renovation: approximately RMB 3 trillion annually

· Infrastructure renewal: approximately RMB 800 billion annually

In this massive wave of urban renewal, upgrading the building sector — one of the largest sources of carbon emissions — has become increasingly important.

Against this background, 5D TECH Energy’s CdTe photovoltaic building materials demonstrate unique advantages.

First, their customizable transparency levels ensure sufficient natural daylight indoors, avoiding the “dark room” problem often associated with traditional photovoltaic curtain walls.

Second, CdTe photovoltaic modules can achieve diverse visual effects through different manufacturing processes, including stone-like, metal-like, and red-brick-like appearances, allowing seamless integration with the renovation needs of aging buildings.

Furthermore, CdTe thin-film photovoltaic cells adopt a long-strip sub-cell design featuring lower current and reduced hot-spot risks, greatly improving building safety. This is particularly important for renovations of existing buildings with high occupant density.

A New Future for Buildings and Energy

As massive existing urban spaces are gradually activated and urban renewal evolves from physical renovation into an energy revolution, the practice of the Hangzhou Digital Energy Port Incubation Building demonstrates a new possibility:

A building can simultaneously become an energy producer, grid collaborator, and reliable energy operator by integrating green power generation, intelligent energy storage, and grid-interactive technologies.

This is not only the success of a single project, but also a blueprint for the future:

Using BIPV to redefine the relationship between buildings and energy, giving every old building the opportunity to become a contributor to a greener world.