Daikin Technology and Innovation Center, Osaka, Japan
Years ago, Japan’s Honda Motor Company coined the word “waigaya,” which is conversation by a large number of people in an open and collaborative work space. The “waigaya stage” in Daikin’s new Technology and Innovation Center enables its 700 researchers and engineers there to more easily collaborate on the company’s innovations.
The primary goal for the Technology and Innovation Center (TIC) in Osaka, Japan, was to design the world’s best multipurpose work area including offices, meeting rooms, and open collaboration space, adjacent to a state-of-the-art, large-scale laboratory to encourage “open innovation”— gaining knowledge from both inside and outside the company. The TIC brings together employees who had been spread across three locations and serves as the chief location for Daikin’s collaboration and technology development.
The core work area of the TIC, which was completed in 2015, supports collaboration by using MIT professor Thomas J. Allen's “30 meter rule,” which demonstrated that there is an exponential drop in the frequency of communication between engineers as the distance between them increases. The “waigaya stage” sits in an open area between floor levels in the center of the office work area.
The design process involved deep collaboration between the company’s engineers and the mechanical design team. The engineers developed innovative products for the new building, and the design team responded by taking advantage of product characteristics to maximize building performance.
TIC is located on the south side of the premises, giving a beautiful view of the river.
Passive design elements, reflected in traditional Japanese building design and informed by the climate, are an important part of the solution (Photos 1 and 2 in gallery). Deep, translucent eaves block direct sunlight in the summer, while allowing visible light to enter. Low-e glass, with good thermal insulation values, and blinds, with automatic controllers that adjust according to the solar altitude, successfully reduce heat loads and optimize natural daylighting. The large office work areas have two large open ceiling areas and two sky lights, which effectively let natural light and ventilation enter the building. Ducts made of glass provide excellent visibility and let natural light enter from the top lights, and creates the shortest supply and return air routes from the rooftop to the office work area (Figure 1). Collectively these efforts reduced the annual energy consumption by 20.5%.
In addition to the architectural methods described, the project team focused on the design, development and implementation of a high-efficiency air-conditioning system. A good example of this is the advanced variable refrigerant flow (VRF) system. In this system, sensible and latent heat are separated by using a desiccant heat pump dedicated outdoor air system (desiccant-DOAS) and a high-sensible heat variable refrigerant flow (hs-VRF) system. The desiccant-DOAS permits individual control of humidity and temperature by the hybrid desiccant element, which contains a water absorption material and a heat exchanger. The hs-VRF was developed for the TIC and was specially tuned to demonstrate high efficiency under low-load conditions, where most of the operation occurs (Figure 2).
Using both hs-VRF and desiccant-DOAS achieves a high COP throughout the year (Figure 3).
In the summer the desiccant-DOAS dehimidifies humid outdoor air (treats latent heat). hs-VRF works only cools (treats sensible heat). In addition, hs-VRF does not need to dehumidify, as the refrigerant temperature can be increased.
In winter the desiccant-DOAS waterlessly humidifies dry outdoor air, absorbing the humidity in the room.
When temperature and humidity are moderate (shoulder seasons), natural ventilation is provided. Both desiccant-DOAS and hs-VRF also provide outdoor air cooling, allowing outdoor air to come indoors.
Combining the passive system reflected in traditional Japanese buildings, and the advanced VRF system, which includes separate latent and sensible heat treatment process, natural energy use such as geothermal and solar heat, and outdoor air cooling, demonstrated high energy savings and comfort in Japan’s diverse climate. Building energy use was 65% less in fiscal year 2016 compared to an ASHRAE Standard 90.1-2007 baseline (Figure 4).
IAQ and Thermal Comfort
Figure 5 shows a psychrometric chart indicating indoor air temperature/humidity and outdoor air temperature/humidity when air conditioners are operating in the office. The desiccant-DOAS and hs-VRF systems are used for individually distributed air conditioning, temperature and humidity control, which are properly and effectively controlled throughout the building.
The “waigaya stage” allows members of the same organization to feel free to discuss issues regardless of their position in that organization.
Since desiccant-DOAS is controlled by CO2 concentration, CO2 values are usually well below 900 ppm. CO2 concentration is lowest when the outside air temperature is around 15°C to 25°C (59°F to 77°F). This means that natural ventilation and outdoor air (free) cooling are functioning well.
Staff surveys were conducted to compare the indoor environment of the previous office locations with the new TIC, and dramatic improvement occurred in all 7 categories (lighting, thermal comfort, air quality, acoustic comfort, workspace, IT and overall environment).
The building’s VRF system (Figure 6) is well integrated with the architecture. The air-conditioning system, which has advanced temperature and humidity control functions and energy-savings, is suitable for various space types. For further energy savings and comfort improvements, underfloor air distribution (UFAD) was installed. It is possible to take outdoor air from the glass ducts in the shoulder seasons for outdoor air cooling, and the underfloor diffusers arranged for each occupant can change the airflow direction according to the occupant’s desire. (Figure 7).
Both the water-heat source and the air-heat source are used with the VRF system in this building; this enables the use of both geothermal and solar heat.
Operation and Maintenance
Since this buildings’ occupants themselves are sustainable product engineers, a carbon management system was developed to disclose building energy management system (BEMS) data to the engineers. Real-time commissioning, with many sensors, using the latest IT technology, was installed to visually show the indoor environment in real time and to make a comparison between theory and practice, which drastically reduces time spent for commissioning and is used for the development of new products (Figure 8).
The TIC project members aimed to provide an office work environment that would enhance intellectual creativity and consume as little energy as possible. Various techniques to reduce energy consumption were adopted, and all of them were applied to the entire building.
The initial investment for such energy-saving and comfort systems was greater than an ordinary office building. The increase in the initial 2013 investment was US$7.2 million or US$33/ft2. The present day utility cost savings are US$534,000 per year, 66% less than an ordinary office building in Japan. Using simple payback analysis, it will take about 13.7 years to pay back the additional investment—assuming utility costs do not increase.
The newly introduced air-conditioning system demonstrates the greatest cost effectiveness. The simple payback period is 5.1 years, compared to the standard VRF system in Japan. The cost effectiveness is an important factor to contribute to global energy efficiency because this system is effective in almost all climates.
Integrated design and energy innovation significantly reduced the carbon footprint of the TIC. The actual reduction in CO2 emissions is 47 kg·CO2/m2 (9.6 lb/ft2) or 65% below the ASHRAE Standard 90.1-2007 baseline . (The CO2 emission factor in Osaka, Japan, for electricity is: 0.509 kg·CO2/kWh).
This building also incorporated high-efficiency water-saving fixtures (water closets: 3.8 L [1 gallon]) water per flush, faucets with: 1.5 L/min [0.4 gallon/min] flow rate and 10 second auto shut-off timers, and rainwater use). Currently, the building consumes 75% less tap water than that of an ordinary office building in Japan. Rainwater is used for all toilet flushing water and irrigation of plants. Additionally, the desiccant-DOAS, which was used to absorb latent heat in the room, almost entirely eliminated the use of tap water for humidification.
TIC has been certified as LEED for New Construction (NC) platinum (v2009).
Daikin believes that, as a member of the community, it is essential to contribute to the development of the whole community to live harmoniously. For example, a small woodland forest has been developed in front of the TIC building so both engineers and neighbors can enjoy the shade of the trees, fragrance of various flowers, and the sound of flowing water.
The challenges of planning a workplace for open innovation and fostering creativity with a low carbon target and improved human comfort were met beyond expectations. Combining the passive system and the new VRF system demonstrated high energy savings and comfort in Japan's diverse climate. Since its completion, over 31,000 researchers and engineers from domestic and foreign countries have visited the TIC. The designers are expecting that this state-of-the-art effort will lead to a reduction in environmental impact on a global scale. •
ABOUT THE AUTHORS
Susumu Horikawa, P.Eng., is a executive officer, principal, mechanical and electrical engineering division, Hiromasa Tanaka, P.Eng., is a general manager of the mechanical and electrical engineering division, and Koji Sugihara is a mechanical engineer at NIKKEN SEKKEI, Japan.