Practical Renovation for net-ZEB Office－Takenaka Higashi-Kanto Branch Office－Nov, 28 2017
Hiroaki TAKAI
Principal Engineer (Environment) , Design Department Head Office
TAKENAKA CORPORATION, Tokyo, Japan

Background
Promotion of “Energy saving
Renovation of Existing middle andsmall stock buildings”
・Company’s branch offices or Local government offices inlocal cities
・Offices with 10,000 m2 or less occupy 98% in Japan・Urgent issues in Japan

Promotion of “Renovation ofFaçade and Interior while staying”
・There are few constructions to completelyrenovate energy saving exterior・Minimization of perimeter thermal load isessential in small office・Renovation while staying is important fortenants

Renovation of Façade andInterior while staying

Characteristics of this renovation project・Net ZEB first renovation project in Japan・Renovation while staying the office that is actually used
・ZEB office with thorough passive
Building Outline
Building type：office
Location ：Chiba City, Japan
Site area：1,432.02 ㎡
Structure･size：RC･S, 2 stories
Height ：8.1m
Building area：679.52 ㎡
Gross floor area：1,318.11 ㎡
Completion ：2003
Completion of Renovation：2016
Design & Built ：Takenaka CorporationExterior of the building after renovation

Interior of the building after renovation

The contents of planning and technologies
・Thorough reduction of Façade Thermal Load・Maximization of utilize Natural Ventilation and Daylighting
・Improvement of Workplace Productivity and reduction of Energy Consumption by Changing Work Style
・Direct utilization of Geothermal and Solar Heat・Increase of comfort by Radiating Air-Conditioning, Dessicant Air-Conditioning, Wellness Control etc.
・Improvement of BCP as a result
Solar photovoltaic power generation panel
Solar heat collection panel
Natural light and ventilationthrough skylight
Desiccant airconditioning for low
humidity

Adoption of double skin structure
Enhanced thermal insulation using
high-insulation glass
Automatic external blind control
Automatic natural ventilation
opening control

Ceiling LED lamps
Radiation airconditioning

Geothermal
heatutilization

Concepts of this office ZEB renovation

Change the theoryof comfort

Create superenergy-saving building

・Maximum use of daylighting, natural vent. & control

・Significant reduction of thermal loadby renovation of facade

・Temperature control by radiant cooling & heating・Humidity control by desiccant air conditioning
・Airflow control by personal diffuser

・LED task & ambient lighting & control
・Ceiling radiant cooling & heating・direct use of geo-thermal
・direct use of solar heat

Think smart work-style

Become resistant
to disaster・Divide into 3 areas in the office・Moving promotion of workers and Work-mode change・Operation time increase,
BCP performance increase

・Environmental setting at each area

・Photovoltaics panel

・Space of common area and Sharing of machines

・Solar heat・Wellness control

・BatteryChange the theory of comfort

Daylighting from both sides

Natural ventilator (auto control)Personal diffuser

Daylighting from top-light

Natural exhaust (auto control)
風向：北温度 ℃
24.
5
24.0

23.5

23.0

22.5

Outside blind (auto control)

CFD of Natural ventilation(Temp.)

22.0

Low humidity by Desiccant
Air-Conditioning

Create super energy-saving building

Exterior

Replace to high insulated glass

Double skin

Radiation panel

Ambient LED lighting 300Lx & Thermal human sensor

Create super energy-saving building

Solar heat panel

Geothermal pile
Radiatingpanel

Desiccant
AHU

SummerRadiating panel Desiccant AHU(re-heat)

Parking
Geo-thermal heat-pump & Air-source heat-pumpwell

Photovoltaics

67m

Geothermal utilization system

Hot water tank

Use for re-heat of desiccant AC in summer

WinterSolar heat panel
Radiating panel Desiccant AHU

Hot water tank

Use for radiating heating in winterSolar heat utilization system

Think smart work-style
Reduction of power outlet consumption
by sharing copy machines and others

Filing area

Communication area

Inactive air-conditioning using ventilation
Work for short 30 minutes

Change of view, angle, andinteractive face each other in variousareas.
Diversity of communication

Workplace
Concentrate on worker’s area.
Lighting and AC are controlled fitting
to personal environment and request.

Entrance area
Change to the office mode in thisarea coming back from outside.
Smooth mode change from public toprivate.

Become resistant to disaster

Devices on the roof

Photovoltaics panel

Solar heat panel

Re-use lithium-ion battery

Actual monthly & annual energy consumption and Photovoltaics(May, 2016 – April, 2017)

MJ/m2・月MJ/m2/month50
40Monthly energy consumption
東関東支店（全館）の月別エネルギー収支実績

年間収支実績
MJ/m2・年
Annualenergy consumption
500
MJ/m2/year
400

Photovoltaics
創エネルギー

30300

202001010001月

2月

3月

4月

5月

6月

7月

8月

9月

10月

11月

0

12月

-10-100ー-20-200-30-300-40-400-50

417

Energyconsumption
消費エネルギー-500403

Actual Primary Energy Consumption（MJ/m2・year）

Comparison before and after renovation -Actual primary energy consumption1600

OthersLighting

Air Conditioning & ventilation

Power Outlet

1400
1200
1000
800
600

Maximum Utilization & Control of Daylighting
Task & ambient Lighting
Several Litghting Control
71％ Reduction
Downsizing Building Services Capacity by Thermal Load Reduction
Direct Utirization of Geo-thermal & Solar heat
Maximum Utirization of Natural Ventilation and Control
Environmental Setting for each areas and Control

4002000-200

Downsizing PC Devices
Sharing of eco-saving
copy machines and others

Before Renovation

After Renovation

3032％ Reduction

After Renovation(Including PV)

In Summary ( ZEB renovation )・We achieved net ZEB at this renovation office・Improved comfort with radiation, low humidity, air flow feeling, bright lightenvironment with daylight・Downsizing of the facade thermal load is very important・Big change of the office layout, change the environment setting point foreach place, share copy machines, and we reduced power outlet
consumption by 70%
・In addition to zero energy cost, overtime hours are greatly reduced by
improving workplace productivity, and payback years is approximately tenyears.
・Effectively utilize geothermal and solar heat

In Summary ( ZEB renovation )・It is important to plan and execute comprehensively thinking about energy
benefit, improvement of workplace productivity by improving work space
recognition and comfort, improvement of BCP, increase of energy cost in
the future, improvement of asset value of building.
・Our future task is further improvement of work style, compatibility between
comfort improvement and energy consumption reduction.