Embodied Energy Analysis of a Pre-cast Building System SECM/15/162 D.M.K.W. Dissanayake C. Jayasinghe University of Moratuwa

Content Background Life Cycle Analysis Embodied Energy of Building Components Methodology Energy consumption at production of building materials (Ep) Energy in transportation of building materials (Et) Energy at construction stage of the building (Ec) Results of Embodied Energy Analysis Conclusion

Background Buildings consume more than 40% of global energy and contributes about 33% of greenhouse gas emissions In European building sector, residential buildings represent about 63% of total energy consumption and 77% of total CO2 emissions (Li et al. 2013) Residential Buildings: 1/3 of building construction in Sri Lanka 92% of occupied housing units, of the country are collectively single storied or two storied 58% of the houses are constructed with brick walls and 33.8% are constructed with blocks Find alternative building systems Environmental restrictions Depletion of resources Cost of labour Depletion of natural resources to acquire -clay, sand, gravel Clay Sand Metal Cement Steel

What level of sustainability can be achieved, with pre-cast concrete? Precast concrete products have become a natural choice of achieving sustainability in buildings, since they incorporate holistic design, efficient use of material and minimize the construction waste and site disturbance. What level of sustainability can be achieved, with pre-cast concrete?

Life cycle Analysis Is a established method, used to quantitatively evaluate the environmental impacts of a product ISO14040:2006 (Environmental Management - Life cycle Assessment - Principles and Framework) So, it is useful to evaluate the LCA of established precast systems in Sri Lanka to understand the actual benefits of them over other building construction methods

System Boundary for LCA of a building MATERIALS CONSTRUCTION OPERATION AND MAINTAINANCE TRANSPORTATION DEMOLITION Embodied Energy Analysis Raw materials and Equipment from ICE database and Work Measurements

Embodied Energy of Building Components Embodied energy is the energy consumed by all of the processes associated with the production of a product, from the mining and processing of natural resources to manufacturing, transport and product delivery. Three main methods of Analysis Process Based Analysis Input- Output Analysis (Economic I-O analysis) Hybrid Analysis Depends on, System boundary of the analysis Geographical location of the study Transport distances and methods Technology of the manufacturing process Method of embodied energy analysis Embodied energy is the ‘upstream’ or ‘front-end component of the life cycle analysis When the product is a building---- product delivery is the padinchi wena awasthawa

Details of the precast building system Precast pre-stressed beams (150mm×350mm) / columns (200mm×200mm) Structure In-situ isolated pad footings with precast pre-stressed tie beams Foundation Ground floor: 50mm G20 screed and 1st floor with precast pre-stressed slab panels (thickness 65mm×1m×4m) Floors Building System Specific Characteristics Windows Timber flamed single glass windows Doors Timber and plastic (PVC) Roof Timber truss and asbestos sheets Ceiling Steel grid, 68% recycled content ceiling tiles (600mm×600mm) Flooring Ceramic Tiles Both interior and exterior walls out of EPS panels (100mm×600mm×2400mm) Walls

Scope of study Ec Et Ep EET A house with identical architectural house plan, built at the same location is assumed for the two building systems. Ec Et Ep EET EET= Total embodied energy Ep= Energy consumption at production of building materials Et= Energy in transportation of building materials Ec= Energy at construction stage of the building

Methodology Prepare the inventory of materials used (using BOQ of the building) Calculate the embodied energy of these materials 3 data sources were used, Sri Lankan data, Indian data , Inventory of Carbon and Energy (ICE database- prepared by University of Bath ) The embodied energy of electrical work and wiring of the house has been eliminated Conduct Work studies and interviews with industry related people to collect data at the construction stage Only equipment intensive activities are considered not labour intensive activities, Fuel usage data for different vehicles used in plants and sites Convert electricity usage, fuel consumption at each activity into energy figures (MJ) Calculate the total embodied energy for the building

Case Study: Two storey residential building Location of the Site: Kandana Floor Area: 325 sq. meters Five bed room house Initial construction: Concrete framed structure with masonry walls( burnt clay bricks) Foundation with pad footings combined random rubble

Energy consumption at production of building materials (Ep) BOQ of the conventional in-situ house  obtain the amount of the building materials Excavation and earth work, ceiling, roof, floor finishes, waterproofing, doors/windows remains same for both systems Material quantities  structural elements such as beams, columns, slabs and wall panel are estimated individually

Embodied energy of metal Data from Finite Lanka (Pvt) Ltd

Main construction materials and their energy density Energy Intensities (MJ/kg) Source Aggregate 0.11 SL River Sand 0.08 Aluminium 155 ICE Cement 4.9 Cement Motar 2.55 Ceramic tiles 12 Sanitary products 20 Bricks 2.3 Wood 10.8 IND Plywood 15 Steel 35.1 Materials Energy Intensities (MJ/kg) Source Stainless steel 56.7 ICE Brass 62 Asbestos 7.4 PVC 105 IND Glass 15 Paints 70 Putty 5.3 Primer 144 Lime 5.63 EPS 36 EU SL: Sri Lanka, IND: India, ICE: Inventory of Carbon & Energy V1.6a

Energy in transportation of building materials (Et) Occur at different stages of manufacturing of products The fuel consumption data and the transportation distances or waiting/idle times at different activities with those machinery related to this building construction were studied. Transportation distances of several construction materials Material Transportation Distance (km) to construction site to redimix plant to precast yard Cement 200 180 Sand 100 Aggregate 50 Steel 30 - EPS Fly ash Bricks 40 Plywood 130 Wood

Energy at construction stage of the building (Ec) Energy usage at construction stage is minimal i.e. most of the work is labour intensive and machinery usage is minimized Frequently Used Machinery  concrete mixer, grinders, bar-cutters, arc-welding plant, electrical drill, etc Record time duration of each machinery in use and its wattage or fuel consumption.

Work Measurements Results of Work Measurements.xlsx Several site visits were arranged to the casting yard at Ekala and some construction sites Work studies were done to quantify Labour, Machinery and Energy involvement at different construction stages Collected data is then used to quantify the embodied energy of materials and products Results of Work Measurements.xlsx Vehicle Efficiencies and usage.xlsx The biggest obstacle for this study is the lack of data availability in Sri Lanka So,

Some photos from site visits 5 6 1 2 4 7 3

Results of Embodied Energy Analysis Embodied energy calculation for the conventional in-situ building Embodied energy calculation for the pre-cast building On site construction activity Embodied Energy (GJ) Excavation and earthwork 2.80 Total in-situ concrete 138.13 Total formwork items 89.20 Total Reinforcement 86.25 Masonry Works 231.13 Floor finishes with ceramic tiles 78.41 Wall finishes (plastering and painting) 280.36 Ceiling construction 128.80 Metal Work 5.63 Roof construction 39.48 Windows/ Doors 49.65 Plumbing & sanitary work 101.49 Total embodied energy of the house 1231.34 On site construction activity Embodied Energy (GJ) Excavation and earthwork 2.80 Total in-situ concrete (10% from in-situ) 13.81 Total formwork items 0.50 Total Reinforcement (5% from in-situ) 4.31 Masonry Works 0.10 Floor finishes with ceramic tiles 78.41 Wall Finishes (painting 50% less) 116.14 Precast concrete elements 453.97 Ceiling construction 128.80 Metal Work 5.63 Roof construction 39.48 Windows/ Doors 49.65 Plumbing & sanitary work 101.49 Total embodied energy of the house 995.10 19% Reduction

Results of Embodied Energy Analysis Results of embodied energy analysis for conventional in-situ building Results of embodied energy analysis for pre-cast building

Conclusion Comparative analysis of embodied energy of a conventional in-situ building system and a precast building system, using process-based analysis was done. Energy consumption at production, transportation and construction stages were considered Total embodied energy of the precast building system (3.06 GJ/m2) is 19% less than the conventional building (3.8 GJ/m2) Further studies on the production process of EPS wall panels and construction stage the energy usage of the building, will help to improve the accuracy of the results.

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