Evaluation of timber as building materials on energy issue and the
Woodmiles: the background and the development of the Woodmiles
Forum in JapanT. Fujiwara*, H. Noda**, T. Shimase**, S. Tachibana**, and T. Takahashi***,Y.
Takiguchi***** Japan Federation of Wood Industry Associations/**Forestry and Forest Products Research Institute of Japan/***The University of Shiga Prefecture/ ****The Woodmiles Forum

Abstract
About a half of newly constructed houses in Japan have wooden structure and timber isconsidered to be one of the important building materials. One of the features of timber asbuilding materials is that very little amount of energy is consumed under production process.
On the other hand, it is pointed out that the energy consumption during timber transportation
processes though long distances is quite larger than that of its production processes.
In order to shorten the transportation distance of the timber used for construction, theWoodmiles Forum was launched, in Japan. The forum is aiming at the development andpromotion of the indexes relating to the distance between the place of harvest of timber and theplace of building.
The Forum proposes several indexes, including the Woodmileage which represent a sum of the
products between the volumes of wooden materials of a house multiplied by the corresponding
actual transportation distances between the place of harvest of the timber used for the
residence, and the Woodmileage CO2 showing the quantity of CO2 discharged in transportation
processes.
It has been two years since the woodmiles movement began in Japan. The knowledge on theindexes have spread throughout Japan during that period, in practical, administrative andacademic field.
The concept of woodmiles would be one of the key words to evaluate the environmental load
for building and transparency of the link between the consumers and the forests.
Keywords: woodmiles, woodmileage, CO2 discharge, transportation, energy consumption,______________________________________
Takashi Fujiwara
Japan Federation of Wood Industry Associations
6F, Nagatacho Bldg, 2-4-3 Nagatacho, Chiyoda-ku Tokyo, 100-0014, Japan
Email: fujiwara@t.nifty.jp
Tel: +81-3-3580-3215 Fax: +81-3-3580-3226

1. Introduction
In order to evaluate environmental load of buildings, in Japan as well as other countries,
sophisticated methods including various kinds of Life Cycle Assessments are being
developed１. These methods are to be adopted as a means of reducing environmental loads
from the construction sites where its building areas reach up to 170 million m2 per annum inJapan.
Up until now it cannot be said that methods developed have spread enough or that there has
been enough reward from massive amounts of efforts. One reason as pointed out is thedifficulty for users of such methods to interpret results from an evaluation despite methods
such as LCA aiming to be quite comprehensive.
The woodmiles index, to be dealt in this paper, was developed by the Woodmiles Forum inJapan to evaluate some aspects of the environmental load of building materials. It may belimited because this index has a restricted range of timber transport distances if considering
this index in regards to evaluations of the environmental loads from buildings. However, it
could give us an opportunity for propagation, because
1) this index provides its users with a simple index of environmental load and2) this index provides a measurement for forming a network of supply of building materials.
We would like to explain the background of this development, its method of evaluation, its
interpretation of results from the evaluation and so forth of the woodmiles index. And we hope
those will contribute much to the fruitful discussions on the evaluation of environmental loads
from buildings.

2. Timber building materials in Japan and its evaluation based on energy
consumption
2.1 Building trends in Japan and trends of wooden frame buildings
In Japan, 173 million m2 of buildings were built in 2003, 63 million m2 of them were wooden
frame buildings. In particular, in the same year, among 104 million m2 and 1160 thousand
units new residential houses, wooden frame houses have 56.3million m2, 523 thousand units
and account for 54.2% and 45.1% respectively of all new houses.
Table 2-1 Trend of Construction Starts of Dwellings
area (thousand m2)

units
year

Total

Wooden
frame

share

Total

Wooden
frame

share

75,11657.0%
1993
1,485,684
697,496 46.9%
131,683
56,34854.2%
2003
1,160,083
523,192 45.1%
104,038
Min. of Land, Infrastructure and Transport, “The Survey on Bldg. Construction Started”

The agricultural areas has more wooden frame dwellings than the urban areas, and the total
ratio of wooden frame houses has slightly decreased in 1980s due to the recent trend in
urbanization. However it has been stable arround 45% since 1990s. (Table 2-1 )If we analyze an opinion survey on the preference of house２, we can see that many Japanesepeople prefer wooden frame dwelling houses. ( Table 2-2 )Table2-2 Preference of house construction
Type of Structure
Preference
Wooden Frame, Traditional
67.0 %
Wooden Frame, 2x4
21.5 %
Non Wooden Frame
7.7 %No answer
3.8 %Office of Public Relation, Cabinet Office of Japan 2003
As described above, wooden frame structures play an important part in building activities inJapan so its trend will not change in the future. Timber itself is one of the most importantbuilding materials in Japan.
2.2 Evaluation of timber energy consumptions and promotion of timber
It is pointed out that one of the features of timber as a building material is its efficiency ofenergy consumption in production processes. Nakajima, S. and Okuma, M. reported that thequantity of carbon emitted from the production of one cubic meter of timber is fur smaller thanthat of other construction materials３. (Table 2-3 )Table 2-3 Energy consumption and CO2 discharge in production process of construction
materials
Material
Sawn timber air dried
Sawn timber kiln dried
Plywood
Particle board
Steel
Aluminum
Concrete

Fossil energy consumed
MJ/kg
MJ/m3
1.5
750
2.8
1390
12
6000
20
10000
35
266000435
1100000
24800

CO2-discharged
kg/tkg/ m3
110
55
205
103
799
440
1129
733
2567
19507
31900
80667
183
440

Nakajima, S. and Okuma, M. 1991
In comparison with each quantity of carbon dioxide discharged from the production ofbuilding materials for such three kinds of building structures as wooden frame, reinforced
concrete and steel frame, Okuma, M. pointed out that the quantity of carbon dioxide from theproduction of building materials for a reinforced concrete house is 4.2 times as much as thewooden frame house, and the carbon dioxide for the steel frame house is 2.9 times as much as
the wooden frame house.４ ( Table 2-4 )Table 2-4 Carbon Discharge on Production of Materials for Construction of a House by Typeof Construction

Materials

Wooden Frame

RC

kg-c
TimberSawn Timber
Plywood
Total
Steel
Concrete
Grand Total

Steel

kg-c

1282.0260.31542.3792.5
2805.15140.0

24.9%
5.1%
30.0%
15.4%
54.6%
100.0%

kg-c

234.6
425.3
659.9
7067.814087.021814.7

1.1%
1.9%
3.0%
32.4%
64.6%
100.0%

293.6
199.6
493.2
8817.15432.714743.0

2.0%
1.4%
3.3%
59.8%
36.8%
100.0%

Okuma, M. "Preservation of Global Environment and Wood Utilization", P.71, in Japanese
Based upon such examination, the timber industry in recent years carries out a campaign
promoting timber as an eco-material５ supported by the related administration. In the Annual
Report 2003 on Trends of Forest and Forestry published by Forest Agency of Japan, there is afeature article of "Toward the new Generation of Wood". The article states that timber is aneco-material that is reproductive with little impact to the environment and is carbon neutral.

3. Sources of timber supply and their distances
3.1 Sources of supply of timber used in Japan and the environmental load from timbertransportation
In 2002, the demand for timber (sawn timber) for Japan was 34,856 thousand cubic meters(log equivalent basis). 70% was used as building materials. From sources of supply, 39% of its
supply was imported to Japan as sawn timber and 29% of its supply was imported as logs forsawing. Domestic timber accounts for 32% of the supply６.
Main sources of imported timber of Japan are North America, South East Asia, Russia(Asian),
Europe and New Zealand. The Table 3-1 shows results of calculations that average thequantity of carbon dioxide discharged from distances of their transportation and its process oftransportation, after analyzing routes of transportations of timbers from its origin７. (Table 3-1)
Table 3-1 Distance and CO2 discharged of transportation of imported timber

Origin
North America
South East Asia

Total

Distance of Transportation km
Sawn Product
Raw Log
boat
car
rail
boat
car
rail

8064
5174

7710
4920

254
254

0
0

0
0

100
0

CO2
kg/ m3
0
0

111
71

1921
22570
9116

Russia7675
Europe23274
New Zealand
9770
Fujiwara, T. et al.(2004)

254
254
554

5000
350
0

0
0
0

500
100
100

0
0
0

Timber from Europe, the farthest major origins from Japan, travels 23 thousand kilometres.
227 kilograms of carbon dioxide per one cubic meter of timber is discharged from its
transporting process. Fig. 3-1 shows a comparison of this figure with the quantity of carbon
dioxide discharged from the production process described in above Section 2８. It is clear thattransportation of timber through long distances has more environmental load than the
production process of the timber has.

250

227

200

177

160

150
111

kg-CO2
100
50

103
71

55

0 ̲̲
d
a
ia
nd
ie
ied
̲̲̲
sia
̲̲
ic
pe
ss
dr
dr
̲̲̲
er
ro eala
̲̲̲
tA
̲
ir
̲̲̲
Ru
n
iln
Z
Eu
a
g
Am Eas
k
it o
r
m
w
r
m
sin
ta
be
rth
th
fro
be
Ne
fro
es
m
or
m
No Soumoc n lu
lu
sp
o
r
m
n
r
f
P
a
m
w
wn
fro
Tr
fro
Sa
Sa

Fig. 3-1 CO2 discharged on transportation and production process
Source: The Woodmiles Forum (2004)
3.2 Comparison of timber transportation distances by importing countries
Further, Fujiwara, T. compared the transportation distances of timbers in importing processes
for three countries Japan, U.S.A. and Germany, using the statistics of trading 2000 by the
Food and Agriculture Organization. The U.S.A. imported the largest quantity of timber in theworld and Germany imported largest quantity of timber in Europe. The Table 3-2 shows
respective quantities of imported timber for each country by distances from the origins９.

Table 3-2 Timber Importation of major importing countries by distance form origin
thousand cubic meters
Distance from
Japan
USA
originTotal import of timber
52009 100.0%
60357 100.0%-1000km
0
0.0%
55889
92.6%
1000-8000km
33393
64.2%
2845
4.7%
8000km18616
35.8%
1623
2.7%
Fujiwara, T. “Woodmiles and house constructed with local timber”,

Germany
22790
9378
13074
338

100.0%
41.1%
57.4%
1.5%

177
227
160

Wood Information, Oct. 2002, Japan Wood Information Center
If the distance of transportation is divided into three categories, U.S.A., which imported 93%
from Canada depends the most imported timber on the nearest sources. Although U.S.A. has
imported valuable timber such as Mahogany and Teak from South-East Asian countries
more than 10,000 kilometres away, it only comprises 3% of the total amount of timber
imported. On the other hand, Japan is one of the few countries that import substantial amountof timber from countries more than 10,000 kilometres away. If we introduce a concept of totaltransporting distance that multiplies imported quantity of timbers and transporting distances,though the quantity of imported timbers for Japan would be less than that for U.S.A., the totaltransporting distances for Japan would be more than 4 times as much as those of U.S.A１０.
(Fig. 3-2)

400
300

３８４
８４

200

J
ap
an

0

５２

６０

１２

１８

U
S
A
G
er
m
an
y

100

Impr t at i o n
Vol u memi l l i o n m3
Woodmi l e age- km* m3

Fig. 3-2 Comparison of woodmileage of imported timber

4. Development of the woodmiles index
4.1 The Woodmiles ForumAs described above, the energy consumed for the transportation process of timber is a criticalfactor in environmental loads and it is especially an important problem to Japanese consumers.
As this problem was brought to their attention the Woodmiles Forum ( here in after refereed as“the Forum”) was founded in June, 2003.
The purpose of the Forum is the development and promotion of the woodmiles index in orderto shorten transportation distances of timber used for building houses and to revitalize local
timber consumption. The Forum's goal is to contribute to realize the sustainable society bypromoting the use of local resources in Japan１１.
4.2 The woodmiles index for the building and its structure
To achieve its objectives mentioned above, The Forum developed a manual to provide a
reproducible and objective method for the calculation of "Woodmiles Index for Building".
The manual revised in December 2004 defines the following four indexes for evaluation ofbuilding construction.

Building Woodmileage
Actual distance covered in transporting timber of the applicable type used in the constructionof a building (hereafter, applicable timber materials) from each place of harvest (timber typespecific wood miles) multiplied by the respective volumes of timber transported from eachplace of harvest (unit: km m3)
Building Woodmileage CO2CO2 emissions equivalent to the energy expended in covering the above distances according to
the types of transportation used (road, rail, sea, etc.) for each form of timber (unprocessed orprocessed) (unit: kg- CO2)
Building Woodmileage L (L = linear)
The linear distance from each place of harvest (timber type-specific wood miles L) of
applicable timber materials to the construction site, multiplied by the respective volumes oftimber transported from each place of harvest (unit: km m3)
Logistics stops knowledge level
The degree, expressed as a proportion of total wood mileage, of applicable timber materials
for which knowledge of processing and storage stops on the way from each place of harvest to
construction site enables the calculation of an accurate woodmileage figure
Because most timber used in house construction goes through a complicated series oftransporting and processing stages, it is invariably only the sawmill that carried out final
processing that is easily knowable, and very little information is available on procurement andpassage of the unprocessed timber. However, this manual demands the maximum possible
elucidation of the processing and storage stops on the way from place of harvest to theconstruction site, together with reasonably concrete measurement of distances between stops,
the form of the timber transported (raw logs, processed timber), and type of transportation
used (road, rail, sea) for each stage. As such, those calculating the indexes will need to trace
the routes taken by the timber used through enquiring at the sawmills, and then the
unprocessed timber market sources involved. This is the aim of the Forum – to bridge thedistance and increase the visibility of the relationship between house builders and owners on
the one hand, and timber producers, transporters and processors on the other. This is also thereason why the Forum has proposed the logistics stops knowledge level index.
However, large part of timber used in construction of ordinary houses are imported fromforeign countries, and in such cases, tracing the route taken by the timber to its place of
harvest is difficult. As such, the Forum has provided a list of provisional values to be used inthese cases.
4.3. Evaluation of new dwelling houses by the woodmiles index
Fig. 4-1 and 4-2 show the result of case studies, using the woodmiles index for building. Fourhouse constructions with local timber in Gifu Prefecture are analyzed. “Ave.” shows
simulation of average house with average timber that is circulated in Japan.

Fig. 4-1 shows Woodmileage for 4 cases. The value of houses with local timber is equal to
1/10th to 1/100th of the average.
450,000

3

Wood mileage [m ・km]

400,000
350,000
300,000
250,000
200,000

379,682

388,077

391,116

402,128

28,71820,323

17,285

6,272

JD7 house

OO' house

HA' house

NA7 house

408,401

150,000
100,000
50,0000Wood mileage ㎥・㎞

Ave.

Reduction from Ave. ㎥・㎞

Fig. 4-1 Case study for value of Woodmileage in house construction
Fig. 4-2 shows the values of carbon dioxide from woodmileage for the cases.
The houses with local timber consume from 3000kg to 6000kg less CO2 than the average
house dose.
The Forum is presenting this figure as followings;
The Government of Japan committed in the Kyoto Protocol to a 6% reduction of the amount ofdischarge of green house gasses as of 1990, in the first commitment period. The amount of C02
discharged in 1990 from the Japanese households is 129 million tons and 6% of it is 6.6
million ton, while the number of household in Japan is 47 million. Therefore 164kg- CO2 isthe reduction amount for each household equivalent to the Kyoto Protocol commitment.
3000kg to 6000kg – CO2 is 20-30 times larger than that.
9,000

Wood mileage CO2 [kg-CO2]

8,000
7,000
6,000

4098

3452

3788

5,000

6040
7778

4,000
3,000
2,000

3680

4327

3990

1,000

1738

0
JD'house

OO' house
Wood mileage CO2 ㎏-CO2

HA' house

NA' house

Reduction from Ave. ㎏-CO2

Fig. 4-2 Case study for value of Woodmileage CO2 in house construction
4.4 The woodmiles index as a tool for business

Ave.

The woodmiles index for buildings can be a tool used by construction companies and builders,
particularly those depending on local timber for their materials, to demonstrate theiradvantages to their clients. The Forum offers construction companies “the Woodmiles Report
Program”. The program includes the evaluation of houses built by the clients with thewoodmiles indexes, and provision of related data including average values of indexes in Japanand in the region, to compare them with the value of the clients’ construction.
If construction companies will seek transparency of distribution of the timber they use, there
will be a possibility that members of the timber industry can disclose information on theorigins of and routes taken by their products, and provide woodmiles values up to theirfacilities.

5. Conclusion: the possibilities and the assignments of the woodmiles
It has been two years since the woodmiles movement began in Japan. Though there have notbeen many applications of the woodmiles indexes, the knowledge on the indexes has spreadthroughout Japan during that period, in practical, administrative and academic field.
As to the practical or administrative aspect, in the last year, some local authorities have justinstituted voluntary system to put labels showing the woodmiles index on building materials.
The annual report of forest and forestry (2003) by the Forestry Agency carried an article
concerning the Woodmileage in the context of eco-materials.
As to the academic aspect, several studies concerning woodmiles have appeared in theconvention of academic societies, including the Japanese Forestry Society, and the Society for
Environmental Economics and Policy Studies (SEEPS). One of the studies was distributed bya news agency with national circulation.
In recent years, in Japan, green purchasing activities have been raised in both public andprivate sectors. It would be getting more important to provide the consumers with reliable
information related to the processes of production and transportation of each commodity. The
concept of woodmiles would be one of the key words to evaluate the environmental load forbuilding and transparency of the link between the consumers and the forests.
The following themes remain for further studies;
1. From the viewpoint of the environmental loads, we will study a unit of transportationenergy that indicates the relation between the transportation distances and the environmentalloads.
2. The potential of the woodmiles indexes to include the concepts of some social or cultural
aspects other than energy issue, including bio-regionalism etc.

１

In recent years, several LCA projects have published their outcome including, theArchitectural Institute of Japan, “LCA Guideline of Building”, 2003, and the Building
Contractors Society, “The report of the activities of LCA Committee”, 2003
２
Office of Public Relation, Cabinet Office of Japan, “The Public-opinion Poll on Forest andLife(2003)”

３

Nakajima, S. and Okuma, M. "Promotion of Wood Utilization for Mitigation of Global
Warming", Wood Industry, Vol. 46, 1991 in Japanese
４
Okuma, M. "Preservation of Global Environment and Wood Utilization", P.71, 2003, inJapanese５
In 2003, June, Japan Timber Industry Association run “Forest and Wood Forum –Tomorrow’s Life and Wood with the Environment “ in Tokyo and Osaka area with over 70
thousand participants.
６
Forestry Agency, “Annual Report of Forest and Forestry (2003)”
７
Fujiwara, T. et al, “Energy consumption due to transportation of timber and policy for local
timber promotion: policy evaluation with the Woodmileage” in Japanese
８
The Woodmiles Forum, “CO2 discharged on transportation of timber by origin andproduction process i” Woodmiles Study Note #3 in Japanese
９
Fujiwara, T. “Woodmiles and house constructed with local timber”, Wood Information, Oct.
2002, Japan Wood Information Center in Japanese
１０
Fujiwara, T. “ditto”
１１
The Woodmiles Forum, “The Goal and Purpose of the Forum”
http://woodmiles.net/gaiyou.htm in Japanese