Physical Input-Output-Tables of the Federal Statistical Office
In the Agenda 21 the conservation of living conditions for mankind was declared as one of the
most important goals in the future. Due to the lack of possibilities of monetary valuation the
environmental functions are highly damaged by production- and consumption-processes.
Therefore it is necessary to add to the SNA in monetary terms a system of accounts using
physical terms, which is made by Physical Input-Output-Tables (PIOT). PIOT are founded on
the law of the physical conservation of matter and energy (first principle of thermodynamics)
and relate to building block B of the SEEA of the UN. In contrast to the SEEA, PIOT are just
regarding flows of materials and energy and no stocks of man-made capital or natural capital.
For Germany a first PIOT was created for 1990 (see Stahmer et al. 1997). In this paper some
fundamental issues of PIOT in general shall be discussed and an overview over the work on
PIOT 1995 should be given.
At present PIOT 1995 for Germany are at work and will be finished soon. The year 1995 is
the latest year for which data for water/used water and waste are available. PIOT 1995 are a
project ordered and financed by EUROSTAT, but it is intended to create PIOT for Germany
regularly every 3-5 years as a part of the material- and energy flow accounting. PIOT 1995
follow for the most part the concept of PIOT 1990 with only little differences. Despite, PIOT
1990 can be hardly compared with PIOT 1995. PIOT 1995 refer to Germany, while PIOT
1990 referred to Federal Republic of Germany prior to unification (the old Länder). Besides
PIOT 1995 follow another classification of branches (WZ93) than PIOT 1990 (WZ79).
PIOT describe the flows of material and energy within the economic system and between the
economic system and the natural environment. They also form an important part of the
module „material- and energy-flow-information-system“ (MEFIS) of the Federal Statistical
Office. MEFIS is a data bank in which all material- and energy flows shall be integrated in
one common system. At present MEFIS is in the stage of implementation. MEFIS will allow
to take better care of the relation of the flows among one another (e.g. combustion of energy
carriers and the resulting emissions) and to get results that are more precise.
The MEFIS-cube (figure 1) contains the different kinds of Physical Input-Output-Tables.
PIOT consist of Input-Tables (which sectors use which materials or pick up materials?),
Output-Tables (which sectors produce goods or give away materials?) and Material­
Integration-Tables
branches.
(Input-Output-Tables),
which
show
the
material-flows between the
Figure 1: The MEFIS-cube
Homo­
Accumulation
geneous
Branches
Non-pro- Rest
Pro­
of the
duced
Private
House- duced natural World
Assets Assets
holds
For energy, water and other materials sub-tables have to be created, because on a highly
aggregated level special problems could not be recognized. On the input-side the sub-table for
energy includes all energy-carriers (fuels) and other materials (e.g. oxygen) which are
necessary for their combustion and transformation. One should use tonnes as well as calorific
values for to show the material-flows (coal, petrol) and to ensure the comparability between
the single energy-carriers. On the output-side are the air emissions, steam and combustion
residues resulting from combustion, and products made from energy-carriers. Water must be
separated because of the quantity of water-flows (about 90% of all material flows) all the
other material- and energy-flows could be regarded as not relevant.
In the following paragraph some remarks are made on the dimensions of the necessary
calculations for PIOT. In the production sphere the domestic production and the import and
export of goods have to be integrated to determine the domestic availability. In this step data
of output in the manufacturing industry by larger enterprises and the data of foreign trade
have to be prepared for the physical input-output analysis. The data of foreign trade can be
integrated without any problems because for every single good (of about 10,800 goods) exist
data in decitons (= 100 kg). Concerning statistics of manufacturing industries there are more
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problems. Corresponding to the foreign trade statistics there are about 6,450 single goods. For
just about half of them are data in units of weight available. The other products recorded in
these statistics have to be converted into tonnes from other physical units - e.g. piece, litre,
square metre - using special average weights. Most of these conversion factors can be arrived
at using ratios from the foreign trade statistics, e.g. ratios of tonnes to pieces or to square
metres. Some of the conversion factors had to be obtained by special investigation or from
supplementary information. In about 10% of cases, ratios of tonnes to DM are used. The
conversion was made at the lowest possible level of aggregation (in practical work an Excel­
file with about 33,000 data sets) so as to minimise the heterogeneity of products and thus the
scope for error in making the conversion. About 1,500 products according to the classification
of input-output-tables are distinguished in PIOT.
Since the statistics for the output of the manufacturing industries normally include larger
enterprises (with more than 19 employees), supplementary estimates were made for smaller
enterprises (with less than 20 employees) on the base of their sales. It is presumed by this, that
the smaller enterprises have the same structure of production than the larger enterprises. In a
next step this quantity must be shared between final products and products, which are
processed into other goods (intermediate consumption).
Concerning the production sphere
PIOT are very similar to the traditional Input-Output-Tables (IOT). This is intended to
maintain the compatibility to monetary IOT as far as possible.
Further additions were required for smaller enterprises in a number of product categories (e.g.
beverages, toys or musical instruments). Data on the weight of new buildings were not found
in the official statistics. Instead, the inputs of building materials for the branches
"construction" and "installation and building completion works" can be used to estimate the
new buildings in tonnes. This output of the construction branches increases the accumulation
of materials and must therefore be posted as an increase in tangible assets.
Moreover, PIOT describe changes in the natural environment caused by human activities like
using of natural assets as source of raw materials and as sink for residuals, on which is drawn
less attention in traditional IOT because of the insufficient possibilities of a monetary
valuation. In agriculture and forestry the PIOT presentation differs markedly from the concept
of the monetary input-output tables. The output of agriculture is represented by the increase of
biomass. It is necessary to make a difference between the biomass needed for consumers`
purpose (cultivated plants and animals) and the biomass that increases the produced natural
assets and the non produced natural assets. For the cultivated plants data of annual harvest
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have been used. For the animals the slaughtered weight was taken for the analysis. To show
the evolution of natural assets data on the change of their stocks are needed, what is difficult
because of the lack of information.
PIOT depict the natural growth of produced biomass as an output of agriculture and forestry.
This results of a metabolic process. The input of this metabolic process are raw materials
(such as water or oxygen) and products like animal feed or fertilisers. These are transformed
into products like meat, eggs, milk or vegetables and into residuals (evaporated water, liquid
manure etc.) which are going back into the nature. The biological metabolism (especially the
photosynthesis) has to be integrated to maintain the identity between inputs and outputs. PIOT
try to depict these flows initially with qualitative evaluation. The essential criterion in the
PIOT for a withdrawal from or discharge to nature is the direct transition from nature to the
economy or vice versa and is ultimately based on the immediate availability of the materials.
The non-produced natural assets are intended to provide an indication of the economic use of
the natural environment.
The withdraws of raw materials from nature comprise not only subsoil assets, but also the
overburden from mining, soil excavated for building purposes, water, oxygen - especially for
combustion - and other materials which are incorporated into the goods during production
and/or which arise as residuals. The subsoil assets withdrawn from nature and often also the
associated quantities of overburden are recorded in special mining statistics and certain
association statistics (Bergbau und Statistik). The overburden which occurs but is not used is
posted at the same level on the input and the output side. Oxygen inputs are estimated on the
basis of the energy carriers burned and the air emissions so produced. Oxygen inputs also
occur in connection with the biological metabolism of human beings and animals.
photosynthesis.
The withdrawal of water from non-produced natural assets, the distribution of water within
the economy, and waste water are an inseparable unit, both as a material flow and from the
point of view of the underlying data. The basic data are the Federal Statistical Office’s
Statistics of Water Supply and Waste Water Disposal. These provide much valuable
information for the construction of PIOT. In the domain of used water there is a conceptual
difference between PIOT 1990 and PIOT 1995, since in PIOT 1995 there is a position for the
flows of used cooling water.
Further calculations had to be made to arrive at the concepts and level of aggregation of the
PIOT. The division of a composite item embracing households, the service sector, agriculture
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& forestry and smaller enterprises of the producing sector (normally with less than 20
employees) proved difficult. To break down this item, investigations were made of water
withdrawal and distribution in particular. These statistics also give results by industry,
whereas the PIOT show them by branch of production. The difference is that industries are
formed of institutions with the same principal economic activity, whereas branches produce
solely the products of a particular category. In order to move from industries to branches, the
quantities of water for secondary activities and the quantities of waste water they produce
have to be transferred to the branches that produce mainly the goods in question.
Since the survey unit for the water supply and waste water disposal statistics is the local unit,
only a few quantitatively significant amounts of water and waste water need to be transferred.
For the purpose of compiling the subtable of water, the withdrawal of water from nature are
first determined for the input-output account’s branches of production, for external
environmental protection services and for households. For larger enterprises of the
manufacturing industries and water supply enterprises, this information can be obtained from
the water statistics (Federal Statistical Office) and association data.
Additional estimates are required, chiefly for agriculture and households, but also for the
unrecorded smaller enterprises and for services. The water input of agriculture is ascertained
from the produced plants and animals using physiological indices. The water withdrawn by
households is estimated from the proportion of the population connected to the water supply.
These calculations give the total water withdrawal from nature andthus an important total for
the water table.
The next step is to determine the water distributed by water supply enterprises. For larger
enterprises within manufacturing industry, information is again available from the water
statistics. The composite item mentioned above for the supply of water to households, etc.
must be broken down to arrive at the PIOT classification. The calculations for smaller
producing sector enterprises, agriculture & forestry and services are based in part on
production and workforce figures and in part on additional information. The distribution of
water to households is obtained as the remainder. When added to the withdrawals of water
from nature, this gives the total fresh water input of the branches and households. The supply
of waste water must also be determined for the branches of production, external
environmental
protection
services
and
households.
For
larger
enterprises
within
manufacturing industry, the waste water statistics (Federal Statistical Office 1995) provide the
basic data.
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The further divisions of the supply of waste water are estimated on the basis of the fresh water
inputs of the various branches. The waste water statistics also show the amounts of waste
water treated internally and externally. For larger enterprises, these data describe which
branches send how much waste water to the branch "external environmental protection
services" for external disposal and how much waste water is treated in the enterprises’ internal
clarification plants. It is assumed that households, the service sector and smaller enterprises
have all their waste water disposed of externally, exceptionally a part which is evaporated or
oozed away. For households at least, this is not entirely true, since in rural areas some
households have their own treatment facilities. However, it is likely that only small amounts
of waste water are involved.
The basis for the presentation of the supply of waste (waste output) and the disposal of waste
in the PIOT is the waste disposal statistics and the waste balance sheet derived from them,
which compare the total amounts of waste produced and disposed of. The first step is to
divide the amount of waste shown in the waste balance sheet among the branches of
production, households and the various tangible assets. The waste produced by larger
enterprises in the producing sector is recorded in the waste statistics.
Like the water supply and waste water disposal statistics, the waste balance sheet shows only
a composite item for the waste produced by households, the service sector, smaller enterprises
within the manufacturing industry, agriculture and forestry (when removed by refuse
collection services). The waste from the smaller enterprises is included by making mark-ups
in line with the supplementary estimates for smaller enterprises in the input of materials and
products. The amount of household and bulk waste produced by households is estimated from
the results of the 1980 and 1985 national household refuse analysis and the key values from
the waste balance sheet. The remainder of the composite item is divided among the service
branches on the basis of selected product inputs.
The amounts of waste produced as shown in the waste statistics also contain waste from
durable goods such as builders’ rubble, scrap, etc. Depending on the type, this waste is shown
as an output of the various tangible assets "buildings" or "machinery and equipment".
Similarly, the waste produced by households is divided into waste from durables and non­
durables. One major type of agricultural waste, namely liquid and solid manure, is not
recorded in the waste statistics. These quantities are calculated on the basis of livestock
numbers and average factors. Liquid and solid manure are shown in the PIOT as discharges of
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other materials into nature. In order to make the transition from waste production to disposal easier, the PIOT distinguish:
· waste for processing,
· waste for treatment and
· waste for landfill.
Waste for processing is an input of the branch "recycling". Waste for treatment is treated (e.g. incinerated) either internally, i.e. in the local unit where the waste is produced, or externally in the branch "external environmental protection services". In the PIOT, all waste for landfill
flows to the tangible asset "controlled landfills". Here, too, most of the data are taken from the waste statistics and the waste balance sheet. There are, however, major discrepancies between the supply and disposal of waste that have to be closed by means of plausible assumptions. For example, only about one half of the excavated soil for construction purposes that is
recorded as waste in the waste statistics is also shown on the disposal side. It is assumed that the unrecorded portion is returned to nature.
There are only rough estimates available of the material inputs and outputs for the biological
metabolism (animals and plants, humans). For these estimates, physiological information is
combined with data on the consumption of products for food. This also provides us with the figures for the consumption of food in restaurants and canteens or the withdrawal of water by agriculture. These calculations cannot be interpreted as "official" results. They should rather
be regarded as rough estimates, which is nonetheless necessary in order to arrive at identical
material inputs and outputs.
PIOT require a combination of economic statistics in monetary units and environmental
statistics in physical units and can be used for a variety of purposes. Any gaps and
inconsistencies become apparent when reconciling inputs and outputs. Another internal use of
PIOT consists in estimating physical data on interrelationship between economy and
environment. Due to the conservation of matter the emitter structure for air emissions is
calculated mainly from energy inputs and emission factors.
PIOT may be used to analyse material flows, showing not only the direct material inputs and outputs of economic activities but also the indirect burdens of production and consumption.
The analysis of direct and indirect material inputs can be applied to scenarios for reducing the consumption of materials in an economy. Besides PIOT can show the evolution of the
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material intensity and the material efficiency of an economy over the time. This could serve
as an interesting indicator for sustainability.
PIOT can be used to illuminate the effects of measures (e.g. laws, taxes) intended to reduce
the consumption of materials and energy. In connection with the monetary IOT the effects of
a change of prices on the quantities of material- and energy-flows can become apparent.
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