1 INTRODUCTION

Portugal is currently facing serious challenges to its production and consumption habits. The country is very dependent on imports for its energy needs, with 87,2 % of the national yearly consumption deriving from external sources (DGEG – Geology and Energy General Directorate, in Portuguese, 2005), and energy efficiency is 25% above European Union’s average with 240 kgoe/1000 Euros in 2004 (EUROSTAT, 2004).

The building construction industry, one of the largest employers in the country, is also considered a major responsible for several negative environmental impacts: energy consumption, associated emissions and waste production. Although the exact amount of construction and demolition waste (CDW) produced each year is not known, estimates point to a value of 4,4 Million tons (Farinha, 2007), the vast majority of which is land filled or illegally dumped. This value of CDW production may be attributed to lack of awareness, lack of other processing options and prevalence of construction habits that do not allow material separation or reuse. In this context, it is urgent to adapt design and construction paradigms to achieve greater resource use efficiency, reducing the amount of embodied and operational energy and also increasing the diversion of CDW from landfills.

Building Deconstruction emphasizes promotion of “reuse” of building materials and components (and even whole buildings) as a way to “close the loop” of materials, and avoid the loss of matter and energy through construction and demolition waste. Whole building reuse is an example of Deconstruction, by disassembling a building and transferring part or the whole of its components to a new site for reassembly. Such operations are quite rare in Portugal and the opportunity to follow and fully document the transfer of the former Lisbon EXPO 98 Macao Pavilion was considered a good subject for a case study in Deconstruction, as it would allow evaluating its environmental and economical profitability.

Building deconstruction in Portugal: a case study A. Santos Faculdade de Arquitectura, Universidade Técnica de Lisboa, Lisboa, Portugal

J. de Brito Instituto Superior Técnico, Universidade Técnica de Lisboa, Lisboa, Portugal

ABSTRACT: This paper presents the transfer and adaptation of the former Lisbon EXPO 98 Macao Pavilion from its original location to a town park in Loures as a case study in building deconstruction. An essential aspect for promoting Building Deconstruction is the demonstration of its multiple advantages, mainly to those directly involved in the designing and building processes, proving the compatibility of deconstruction friendly principles with architectural expression, functional efficiency and economical profitability. A description of the disassembly and reassembly operations of the former Macao Pavilion is made, identifying the main difficulties found. An analysis of the overall profitability of the operation is also made, estimating the amount of material diverted from landfill and the amount of embodied energy saved through material reuse. An economical profitability study compares the costs of disassembling and reassembling the pavilion with those of a new building.

2 BACKGROUND

The Lisbon Expo 98 Macao Pavilion was designed by RISCO architectural design office in 1997 and was built in the northern central part of the EXPO 98 exhibition grounds, alongside the main pedestrian avenue, on a rectangular eastern facing sloping plot surrounded on three sides by streets while the north side opened to a another building plot (Figure 1).

Figure 1: The former EXPO 98 Macao Pavilion (Southeast view) in its original location in May 2005.

The Pavilion was a two-story building, with an doubly symmetric 55 x 30 meters rectangular

shaped plan, comprising two “blocks” with two floors each. The eastern block housed exhibition spaces and was open at the street level, while the western block also housed exhibition spaces and administration / reception areas in the enclosed lower floor. Both upper levels were linked by two partially enclosed elevated walkways, which defined a patio between both blocks. The whole building had a structure of bolted metallic elements ranging in cross-section from HEA 600 to IPE 200, with enclosing walls made of 22 mm thick wood-cement viroc panels supported by metallic frames bolted to the main structure, except for the lower western block which had a brick encased metallic structure and brick partitioning walls. The floor of the upper level was made of 3 cm thick Medium Density Fiberboards and solid pinewood boards, while the roof was integrally made of corrugated metal panels, with metal rain gutters and eaves. Interior finishes (ceiling and walls) were gypsum board drywalls, including 60 mm rock wool insulation. The upper volumes had no windows, the only glass being present on the doors and panels that enclosed the street side of the elevated walkways. Windows and doors on the lower volume were double-glazed and aluminum framed. After the exhibition’s end in October 1998, the pavilion was vacated and closed. In late 2004 it was bought by the Loures municipality to be reassembled in the new town park of Loures and used as a teahouse / art gallery.

3 DISASSEMBLY

Disassembly started in May 2005, taking place in three main stages over a period of approximately 14 weeks up to mid-August 2005. During the first stage, interior finishing materials were stripped, sorted by type and piled on the elevated walkways since the patio was unavailable as a sorting and stocking point. Building systems were also disassembled at this time. Doors, hardware, fixtures, cabling and piping were removed for reuse or recycling. Metals (soft steel, copper wiring) were sold to scrap metal dealers; wooden materials were removed to be used as fuel; other materials (rock wool, gypsum) were land filled.

The second stage of the disassembly took about four weeks and consisted on the dismantling of the building’s external envelope, made possible since the removal of the interior finishes had exposed all of the internal connecting points for the external façade support frames as well as the roof panel’s fixings. At this point, unfamiliarity with disassembly operations led to time losses as some elements were “over disassembled” rather than kept as whole components, while there was no properly established identification system for the parts.

The third stage of the process consisted on the disassembly of the steel structure. All of the elements of the steel structure were bolted, which allowed and facilitated disassembly, and were of a manageable size, which allowed manipulation and transport with commonly available means. The external access ramp, composed of two 24 meter long trusses, had to be cut in two for transport, while the main pillars bolting plates were found to be encased in concrete, and had to be cut making. A final step of the disassembly process consisted on the demolition of all reinforced concrete (foundations, ground slab and retaining wall) and brickwork walls.

In conclusion, the configuration and constructive solutions, such as assembly sequence, geometry of product edges and connection methods (Durmisevic, 2003) allowed for a systematic separation of building materials. A more thorough audit prior to disassembly would have identified materials, components and sub-assemblies worthy of disassembly and transport, an action that might have increased the profitability of the operation, as the value of harvested materials is usually inversely proportional to the number of disassembly steps necessary to acquire them (Durmisevic, 2006). A more effective labeling system for identifying components and their connections would also have benefited the whole operation, as it was later estimated that a more effective labeling of parts would have reduced reassembly time as much as 25%.

4 REASSEMBLY

The contract for reassembling the metal structure and build a new exterior enclosure was won by the Somague company, with reassembly started in the spring of 2006 and still ongoing in May 2007 (Figure 2). The reassembly was slowed down by a variety of factors namely because the materials transported had been piled up exactly on the building’s future location alongside a general lack of information on the building design (original plans were not found on the architect’s archives) and deficient or inexistent labeling of parts .

During rebuilding it was discovered that a few medium sized elements from the main structure were missing, and it was necessary to produce similar ones. New structural elements also had to be produced to replace those that had been encased in brickwork, while the original (and shortened) main pillars received new bolting plates.Other changes to the original project included the introduction of an intermediate steel deck.

Other than the structural steel elements, little was reused from the originally transported parts, either because materials had already been reused (“viroc” wood-cement panels were applied in the back facade of the St. Paul church scale reproduction), because they were unnecessary (façade substructures were not needed, as infill walls were now to be made of ceramic brickwork) or because they were unusable (asphalt contaminated roof panels).

Figure 2: General view of the pavilion being rebuilt in Loures as of April 2007.

5 ENVIRONMENTAL PROFITABILITY

Although it is fairly obvious that an operation of disassemble / reassemble should be environmentally preferable to a straightforward demolition, it is essential to determine exactly the benefits of such operations in order to promote design for disassembly and material reuse. There is no voluntary building environmental rating scheme in use in Portugal (such as BREEAM, LEED or Green Building Tool), and therefore there is no immediate methodological framework to evaluate the benefits associated with reuse of building components or materials.

Guy (2003) has proposed a Green Demolition Certification Draft, consisting of a credit system, rating actions at Building, Planning and Environmental Health and Safety levels of the demolition process. The system proposes the attribution of a green certificate on attaining 25 of the 52 possible credits, while setting minimum pre-requisites such as a mandatory 20% material diversion from landfill independently of building size. The literal application of this certification draft was deemed inadequate in this particular case, nevertheless the environmental profitability of this operation was evaluated on two of the most “valuable” rating aspects of the rating scheme: diversion of materials from landfill and embodied energy saved.

5.1 Materials diverted from landfill

The original complete bill of materials of the pavilion having been lost, a new bill of materials was calculated from EXPO archive project drawings and partial RISCO files. This allowed an estimation of the quantities of materials present in terms of weight, with composite elements (window units, facade panels) being broken into their main materials. Smaller components (bolts, door handles, etc.) were ignored for these calculations. Materials associated with building systems such as HVAC, rainwater drainage, water supply and residual waters were not considered given their low relative weight or impossibility to decompose into basic materials (as in the case of air treatment units).

In calculating the mass and weight of the materials, several references were used (Farinha, 1997), as well as catalogues and technical information reference material. Weights of structural elements (steel and concrete) were taken from the original structural bill of materials. The pavilion weighted a total of 1.820 tons, with 75% of that value being reinforced concrete present in foundations, ground slab and retaining walls (Figure 3).

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Allocating the different materials per waste processing option (Figure 4), it becomes

apparent that only 10% of the materials were reused (the steel structure and viroc panels), while a total of 14% were diverted from landfill (through a mix of reuse, recycling and energy recovery). While these percentages would not meet the minimum requirements of the Green Demolition Certification draft mentioned, it should be noted that almost all of the main constituting materials were adequately separated and thus the lack of a higher diversion rate from landfill could be attributed to lack of processing options and not to project or process characteristics.

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Figure 4: Volume of material per waste processing option.

5.2 Embodied energy savings

Another complementary assessment of environmental profitability of the transfer / rebuild

operation is to quantify the amount of embodied energy saved. Treloar (1998) defines embodied energy as “the quantity of energy required by all the activities associated with a production process, including the relative proportions consumed in all activities upstream to the acquisition of natural resources and the share of energy used in making equipment and other supporting functions, i.e. direct plus indirect energy”.

In the context of this study, embodied energy was understood as “process embodied energy” and not “gross embodied energy”, thus excluding energy used to transport the materials and workers to the building site, upstream energy input in making the materials (such as factory / office lighting, energy used in making and maintaining the machines that make the materials, etc.) or embodied energy of urban infrastructure (roads, drains, water and energy supply). Process embodied energy values for construction materials can vary greatly since there are many different combinations of possible input / output paths to attain a certain embodied energy value per unit of material. Studies (CSIRO, 2003) have identified the following variables affecting embodied energy calculations: efficiency of manufacturing process; fuels in manufacture of materials; distances of transport and amount of recycled product used.

Embodied energy values are considered useful as an additional decision factor when comparing different building materials for a specific design problem, ideally complemented by environmental impact reference materials, since a low embodied energy material may be less favorable than another with higher energy content for a variety of reasons (lower technical service life, reciclability, etc.). Nevertheless, given the demonstrational character of this study, it was considered useful to demonstrate potential energy savings in this building transfer operation by calculating the amount of embodied energy preserved in reused building materials.

The previously calculated material volumes were converted into MegaJoules using several reference tables for embodied energy values per unit of mass. Since there are no specific embodied energy tables for construction materials in Portugal, the closest comparable source was used, namely the tables of the Spanish Instituto para la Diversificación y Ahorro de la Energía (IDAE), as cited by Gonzalez (2006). These reference values were considered to be very reliable as Spain and Portugal have similar geographic conditions, construction habits and construction material usage. In the only instance where a value for a material used in the Macao

Pavilion was not available in these tables, data from the New Zealand Institute of Architects “Comparison of building elements - Life cycle analysis” database (1995) was used. In calculating the embodied energy of steel elements a value of 14,25 MJ/kg was used, as a mean average between the values of 35 MJ/kg for virgin material and 10 MJ/kg for recycled source material considering that 83% of current steel is recycled or of recycled content (Steel Construction Institute, 2002). The original pavilion materials thus corresponded to a total of approximately 5.630.000 MJ of embodied energy, distributed according to Table 1.

Table 1: Embodied energy present in the original building, including waste processing options (RU - reused; RE - Recycled; LF - Land filled; ER - Energy recovery)

Weight (kg) MJ/kg Energy (MJ) Option Structural elements Steel structural elements 159.900 14,25 2.278.575 RU Reinforcing steel rods 38.360 10,00 383.600 RE Concrete (B30) 1.383.120 1,20 1.659.744 LF Exterior walls Perforated ceramic brick wall, 30 x 20 x 20 cm, with cement / sand mortar render 5.384 2,50 13.460 LF Perforated ceramic brick cavity wall, 30 x 20 x 15 + 30 x 20 x 11, with cement / sand mortar render 35.148 2,50 87.871 LF Cavity wall insulation rigid PU board (30 mm) 71 72,20 5.147 LF VIROC wood-cement facade panels (22 mm) 18.701 9,50 177.657 RU 50 x 50 x 4 RSH facade panels metal frames 7.075 14,25 100.813 RE Interior walls Perforated ceramic brick wall, 30 x 20 x 11 cm, with cement / sand mortar render 33.587 2,50 83.966 LF Interior single 12,5 mm plasterboard wall (inc. substructure) 7.612 6,10 46.431 LF Rock-wool insulation (60 mm thick) 1.305 14,60 19.051 LF Floor finishings Cement sand screed, smooth finish (100 mm) 67.859 1,20 81.430 LF Ceramic mosaic 10 x 10 cm 170 2,50 425 LF Pinewood floor baseboard (20 x 70 mm section) 122 2,00 244 ER Solid pinewood floor (30 mm) 3.936 2,00 7.873 ER Moist resistant MDF boards (30 mm) 14.388 11,90 171.214 LF Ceiling finishings Interior suspended plasterboard 9.709 6,10 59.223 LF Exterior moist resistant suspended plasterboard 10.237 6,10 62.444 LF Rock-wool insulation (60 mm thick) 2.459 14,60 35.905 LF Stonework Door sills (average thickness 4 cm) 1.801 6,00 10.805 LF Doors and windows Glass 4.720 15,90 75.041 RE Aluminum frames 280 191,00 53.461 RE Steel frames and doors 4.261 14,25 60.715 RE Various steelwork Exterior hand-railings 1.235 14,25 17.592 RE Roof panels, corrugated sheet metal "Alaço" type 7.809 14,25 111.271 LF HVAC protection perforated panels, inc. substructure 1.230 14,25 17.524 RE 1 mm zinced water-drains and eaves profiles 251 14,25 3.583 RE

TOTAL 1.821.482 5.630.036 According to the various disposal options for the different materials present in the Pavilion,

it can be observed that 43% of the total EE value, corresponding to 2.450.000 MJ, was preserved due to the steel structure being reused. Considering the loss of 10-15% of the original steel components of the building, nevertheless approximately 2.200.000 MJ of embodied

energy may have been saved. The production of this energy from fossil fuel would correspond to approximately 52,5 tons of oil equivalent (1 toe = 42 GigaJoules), whose combustion would release (on average) approximately 45.000 kg CO2 to the atmosphere. The amount of energy saved corresponds to 680.000 KW/h, which would cost 75.000 Euros (at current national rates).

A comparison made using values from Portugal’s General Directorate for Energy “Energy Consumption Management Regulation” (1995), which stipulate maximum tons of oil equivalent to be spent in the production of certain construction materials, yielded steel embodied energy values almost 20% higher than those obtained through the Spanish IDAE values.

As mentioned earlier the embodied energy values considered do not account for energy from transport, and so the added energy from the trips necessary to transport the pavilion steel components was not considered. However, it is important to refer that if this transport energy were accounted for, the option to reuse would be even more favorable than new building since there is no source of steel elements closer to Loures than the Expo site (the sites are just 18 km apart). CO2 emissions and embodied energy due to transport corresponded respectively to 550 kg CO2 and 56 MJ, from the 200 l of diesel estimated to have been used in the 20 two-way journeys to transport the structure (consumption and distance obtained in www.mappy2.com).

In conclusion, although only a low percentage of the total material volume of the existing building was reused, it did correspond to over 40% of the total estimated embodied energy present, which constituted a considerable environmental and financial saving.

6 ECONOMICAL PROFITABILITY

Parallel to the environmental benefits estimation, an equally important assessment (some would argue, the most important one) is that of the economical profitability of this operation. The Loures municipality paid a total of � 260.000 (excluding taxes) for disassembly, reassembly and construction of a new enclosure. The pavilion itself was donated, an obvious choice for the owner as the property becomes available for redevelopment at zero cost.

An economical profitability study must compare the values paid for actually (re)used elements to the value of supplying and assembling new comparable products. As seen before, material reuse was limited practically to steel structure elements, of which the original pavilion possessed 160.000 kg. Considering a 10% replacement rate for lost parts and 24.000 kg to replace the elements that were originally encased in brickwork (estimated from the original bill of materials) a total of 200.000 kg present in the new pavilion is obtained.

Considering that the value of the new foundations, enclosure walls and roof (which should be discounted) is equal to the price paid for the road transport of the elements (which should be added), an average value of 1,30 Euro paid per kg of steel is obtained.

If a fully similar building were to be built anew, the budget of supplying and assembling 160.000 kg of steel structure (the original amount needed) would be � 528.000 using 2006 average tender prices of � 3, 30 per kg of steel. If the original 198.000 kg of steel (160,000 kg from the structure plus 38.000 kg of reinforced concrete bars) had been sold for recycling, it is reasonable that a price of 0.5 Euro/kg would have been paid, resulting in a net total of 429.000 Euro to be paid for a new pavilion.

Considering both the least and most advantageous relationships between the aforementioned values, the disassemble / reassemble option is always more profitable (for the owner), with prices 65 to 100% lower than the price of an all new structure. It is interesting to consider that if a reinforced concrete structure had been used in a new similar building, the estimated cost (from average prices per sqm of construction) would have been approximately 295,000 Euro, a value still higher than the 260.000 Euro paid by the municipality.

7 CONCLUSION

Although the disassembly and reassembly of the former Lisbon Expo 98 Macao Pavilion was affected and slowed down due to the novelty of the process, the balance was nevertheless positive on both economical and environmental aspects. A low 14% diversion rate from landfill was achieved, but the materials reused amounted to almost 40% of the total embodied energy

present. Economically the operation was profitable on all levels, and a more efficient planning on disassembly would have raised the profitability of the operation even further.

Studies (Boyle, 2005) have shown that transport and degree of waste processing infrastructures are the main conditioning factors to salvaged material reuse overall profitability. In the Macao Pavilion case, the very short distance between disassembly and reassembly sites reduced the negative impacts of transport, but the lack of appropriate disposal options greatly hindered the degree of diversion from landfill. This was made more evident since the original design was very favorable to deconstruction, permitting an effective reversal of the building sequence and allowing a high degree of material separation.

This operation was greatly facilitated by the fact that it was promoted by a public body which eased bureaucratic procedures, as no project and building permits were required, while the “whole rebuilding” option allowed bypassing structural calculations and verifications. A mention must also be made to the overall architectural strategy as it allowed functional adaptation with little effort, benefiting from the typology of the building (an isolated building).

This study shows that in more urbanized areas of Portugal, where building habits are more developed, more sophisticated building techniques are available and transport networks are more dense, it may prove profitable on all dimensions to design all steel structure buildings that allow disassembly and transfer, thus obtaining a higher construction material usage efficiency, and ultimately a more sustainable construction.

In order to achieve this ultimate objective, further efforts are necessary in many areas, including raising awareness of stakeholders, laying down appropriate legal framework, creating adequate processing infrastructures and raising the consciousness of designers and builders.

8 ACKNOWLEDGMENTS

The authors wish to express their thanks to all who aided in gathering the information necessary to accomplish this study: Eng. Silveira e Castro and Mrs. Maria Helena Figueiredo from the ParqEXPO company; Arch. Madalena Duarte Silva and Arch. Inês Cruz from RISCO architectural design office; Eng. Miguel Abecasis from TalProjecto structural design office; Eng. João Carvalho from Teixeira Trigo structural design office; Eng. João Caramelo from EACE technical engineering design office; Eng. Eunice Barreiros, Eng. Manuel Domingos and Arch. João Lomelino from the Loures Town Hall and Eng. João Gamboa from Somague construction company.

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