Net Zero Energy Building (ZEB) Certification

Efforts in Net Zero Energy Buildings (ZEBs)

Osaka University stipulated its goal of achieving ZEB Ready (energy saving of 50% or more) for its new building construction on campus in its Mid-Term Goals and Basic Policies in Energy Management, which was established in February 2021, ahead of other universities in Japan and is actively promoting ZEB to lead the way towards carbon neutrality.

Mid-Term Goals and Basic Policies in Energy Management at Osaka University

Certified Buildings

Osaka University and Nippon Foundation Center for Infectious Disease Education and Research (to be completed in February 2025) -- Certified as ZEB Ready Building

• Basic Design/Design Supervision: Tadao Ando Architect & Associates
• Basic Plan: Osaka University, Meiho Facility Works Limited
• Design/Construction: Taisei Corporation and Nikken Sekkei Joint Construction Venture (Design-build contract)
• *Note: Reproduction of the above perspective drawing is prohibited.

Building Overview

• Project type: Newly-built
• Date of completion: February 2025 (planned)
• Total area of the new building: 17,618.36 m² (at the time of designing)
• Construction: Steel-reinforced concrete with partial steel framing
• Floors above ground: 10
• Date of Evaluation: September 20, 2024
• Building Energy Index (BEI): 0.45

Osaka University and Nippon Foundation Center for Infectious Disease Education and Research (Issued on September 20, 2024)

Efforts made to achieve ZEB

This building was certified as "ZEB Ready" by installing:

• Horizontal louvers that cover the entire building
• Low-E glass
• Inverters to control the speed of a fan motor
• Draft chambers with high-speed variable air volume (VAV) control
• Highly efficient air conditioning equipment with high coefficient of performance (COP)
• Total heat exchanger units that control the ventilation rate using sensors that measure the concentration of CO₂ in indoor air
• LED lighting
• Light control with motion sensors and brightness sensors that detect the surrounding lighting conditions

Through these efforts, the "design primary energy consumption" of this building is 55% less than the "standard primary energy consumption."

Toyonaka Co-Creation Building B, Toyonaka Campus (to be completed in March 2025) -- Certified as "Equivalent to ZEB Ready"*

Toyonaka Co-Creation Building B, Toyonaka Campus, Osaka University

Certification of the Building-Housing Energy-Efficiency Labeling System (BELS) for the Center for Development of Co-Creative Environment (tentative name) (Issued on January 18, 2024)

Building Overview

• Project type: Newly-built
• Date of completion: March 2025 (planned)
• Total area of the new building: 5,047 ｍ² (new building)
• Construction: Steel-reinforced concrete with partial steel framing
• Floors above ground: 7
• Date of Evaluation: January 18, 2024
• Building Energy Index (BEI): 0.48 (new building)

Efforts made to achieve ZEB

This building was certified as “equivalent to ZEB Ready” by installing:

• Multi-layered glass to improve thermal insulation performance
• Multi-split type air conditioners for buildings that are operated with high COP (coefficient of performance)
• Total heat exchanger units that control the ventilation rate using sensors that measure the concentration of CO₂ in indoor air

For air conditioning, the "design primary energy consumption" of this building is 59% less than the "standard primary energy consumption."

For lighting equipment, the "design primary energy consumption" of this building is 67% less than the "standard primary energy consumption" through the introduction of LED lighting and light control with motion sensors and brightness sensors that detect the surrounding lighting conditions.

*Note

Toyonaka Co-Creation Building B will be connected to the existing Interdisciplinary Research Building via a passageway, so the combined building will be considered a single building under the Building Standard Act.

Since the Building-Housing Energy-Efficiency Labeling System (BELS) uses an evaluation method that complies with the Building Energy Efficiency Act, which is based on the Building Standard Act, ZEB and BELS are evaluated using BEI, or the ratio of design primary energy consumption to standard primary energy consumption. Energy consumption is calculated based on building energy consumption performance of the combined two buildings.

Although the new building combined with the existing building has not been certified as ZEB Ready, since the BEI for the new building meets ZEB Ready requirements, we consider this new building to be “equivalent to ZEB Ready.”

MA-T Co-Creation Center -- certified as ZEB Ready on a national university campus

Building Overview

• Project type: Newly-built
• Date of completion: January 2022
• Total area: 3,389ｍ²
• Construction: steel framing
• Floors above ground: 4
• Date of Certification: October 22, 2021
• Building Energy Index (BEI): 0.49

Efforts made to achieve ZEB

This building achieved a standard ZEB not by introducing special equipment but by lowering energy consumption through the optimization of air-conditioning loads and electricity capacity as well as the improvement of thermal insulation (by using thermally insulating double glazing and introducing high efficiency equipment, such as high efficiency air conditioners and LED lights.)

Equipment installed

Air conditioning/ventilation

Small, low-power indoor casette-type air conditioning units were installed in optimal locations throughout the building.

Total enthalpy heat exchangers make use of CO₂ sensors to control fan speed depending on the number of individuals in the room.

Openable skylights

Openable skylights are installed in the atrium space on the 4th floor in order to prevent buildup of heat, save energy through use of natural lighting, and emit smoke.

MA-T Co-Creation Center (Formerly Building 4, School of Pharmaceutical Sciences) is cited as a Zero Energy Building Example (#25) on the website of MEXT. (link in Japanese)

Research and Education Hub, Minoh Campus -- certified as ZEB Oriented

Building Overview

• Project type: Newly-built
• Date of completion: December 2020
• Total area: 24,897㎡
• Construction: Steel/steel-framed reinforced concrete
• Floors above ground: 10
• Date of certification: March 31, 2022
• Building Energy Index (BEI*): 0.58

*Building Energy Index (BEI): the ratio of the total amount of energy consumed by a building in a year over the built area of the building measured in kWh/m²/year. ZEB Ready is defined as a 50% energy-saving building, which is a minimum requirement of ZEB.

Efforts made to achieve ZEB

Energy conservation has been achieved through use of high COP (coefficient of performance), high efficiency multi-split air conditioners designed for use in large buildings as well as low-fan power casette-type indoor units.

Lighting for the building incorporates LED lighting, motion detectors, and automatic dimming based on brightness of the surrounding area.

The exterior of the building uses high performance glass that blocks 70% of solar radiation heat and provides 3 times better heat insulation when compared with conventional clear glass.

In addition, incorporating brace beams to the exterior of the structure (forming an outer-frame type structure) provides for a visor-like effect to shield against direct sunlight to the building. By taking in light while cutting heat to the building, it has become possible to cut energy use for both lighting and air conditioning.

What is ZEB?

Zero Energy Buildings (ZEBs) are defined as buildings that aim to achieve annual primary energy consumption balance of zero while maintaining operations by saving energy as well as creating energy through the introduction of recyclable energy and other means.

The Ministry of the Environment classifies buildings into the following 4 categories based on environmental performance.

Reference

• Defintion of ZEB (MOE ZEB PORTAL) (link in Japanese)