Many building materials are used for construction and different methods are followed. Each of these building materials has a unique embodied energy. Out of these materials, Roofing material constitute one of the major energy consuming components of the building. Effective utilization of available energy and its conservation is global challenge. For a developing country like India, the increasing demand of energy has created a scope for the study embodied energy of alternative roofing technique and their advantages for the sustainable building construction. The total embodied energy of a building can be reduced significantly by using alternate roofing technique such as RCC Filler slab which has lower embodied energy value. Filler slab technology is a simple and a very innovative technology for a slab construction. The filler slab is based on the principle that for roofs which are simply supported, the upper part of the slab is subjected to compressive forces and the lower part of the slab experience tensile forces. Concrete is very good in withstanding compressive forces and steel bears the load due to tensile forces. Thus the lower tensile region of the slab does not need any concrete except for holding the steel reinforcements together. Hence concrete in the bottom region of solid RCC slab is replaced by an energy efficient and cost effective material. With reduced consumption of building material for roofing, the cost of the building can be reduced predominantly.

1. Filler Slab Roofs
AN ALTERNATIVE ROOFING TECHNIQUE

2. What is EMBODIED ENERGY?
 Energy consumed in the production of basic
building materials
 Energy needed for transportation of the building
materials
 Energy required for assembling the various
materials to form the building
Construction sector in India is responsible for major input of
energy resulting in the largest share of CO2 emissions (22%) into
the atmosphere.
The Need for Alternatives

3. The Concept

4. Replacing unnecessary concrete in the tension zone with filler
material suitably

5. Filler material selection
• Filler material should be inert in nature. It should not react with
concrete or steel in RCC slab constructed.
• Filler materials water absorption should be checked for as it will soak
the hydration water from concrete.
• Filler material should be light in weight, so that overall weight of the
slab reduces and also the dead load onto the foundations is
reduced.
• Filler material should be low cost so that it cost is much lesser then the
cost of the concrete it replaces.
• Filler material should be of a size, cross-section and thickness which
can be accommodated within the spacing of the reinforcement and
cross section of the slab.
• Filler material texture should match with the desired ceiling finish
requirements so as not to provide an ugly ceiling pattern.

6. Installation of Filler material
Filler materials should not be installed at the shear zone.
 Clear distance of 150 mm from end supports in all directions.
 Gap of about 75 mm between each unit of filler material.

7. Stabilized Mud Filler Blocks
as Filler material

8. Mangalore Tiles
as Filler Material

9. Laying Earthen Pots as
Filler material

10. Ceiling when Earthen Pots
used as Filler material

11. Terracotta Roofing
tile as Filler material

13. Plan and Section of RCC Filler Slab

14. Sl.
No
Material Embodied
Energy (MJ)
Conventional
Roof
Filler slab
roof
Quantity
consumed
Total
Embodied
energy (MJ)
Quantity
consumed
Total
Embodied
energy (MJ)
1 Concrete
Cement (kg) 5.85 8453 49452 6847 40055
Coarse aggregate (m3) 108 19.15 2068 15.51 1675
Fine aggregate (m3) 87.5 10 837 7.76 679
2 Reinforcing Steel (Kg) 42 564 23689 349.58 14682
3 Mangalore Tile 5 0 0 1469 7345
Total Embodied energy (MJ) 76047 64436
Difference of energy (MJ) 11611
Percentage saving of energy 15 %
ILLUSTRATION
Embodied energy calculations for a 200 sq.m slab of 100 mm thick.

15. 76047 MJ
64435 MJ
58000
60000
62000
64000
66000
68000
70000
72000
74000
76000
78000
RCC Slab Filler Slab
Energy(MJ)
Embodied Energy for a 200 sq.m slab
RCC Slab Filler Slab
Now 1 kw = 3.6 MJ
 Therefore a saving of 3220 kwH of electricity
equivalent is achieved
 This is equivalent to 0.28 tonnes of oil saving
 This is equivalent to 3.22 tonnes of CO2 gas
released to atmosphere
 This is equivalent saving of 4800 hours of AC
electricity consumption or 200 days

16.  Consumes less concrete and steel due to reduced weight of slab by the introduction of a less
heavy, low cost filler material.
 Filler slab technology can also be applied to mass housing projects and township projects to gain
high cost saving and also saving in high energy consuming materials.
 This can be of a better thermal comfort if a cavity is kept between the filler material or the filler
material itself has a cavity.
 Filler slabs can be kept exposed (with proper workmanship) to create aesthetically pleasing ceiling
with a view of filler material from below and thus the cost of plastering and/or painting also can
be avoided.
 Reduction in concrete quantity compared to conventional slab construction, adds this technology
to the list of sustainable and environment friendly technologies and with green building features.
ADVAVNTAGES

17. CONCLUSION
It is possible to save on approximately 19% of the total concrete and
including the cost of filler material and around 5-10% of your concrete cost
If the filler material is just a waste material, it saves upon nearly 15% on
roof concrete construction cost.
The total embodied energy of the can be significantly reduced by about
15% when compared with solid RCC slab thus conserving the energy.

18. THANK YOU