Embodied energy of building envelopes and its influence on cooling load in typical Indonesian middle-class houses Agya Utama and Shabbir H. Gheewala JGSEE The J oint G raduate S chool of E nergy and E nvironment (JGSEE) King Mongkut’s University of Technology Thonburi, Bangkok, Thailand

Introduction  50% from the total 24,000 MW capacity  80% in Java and Bali island  Electricity in residential sector in Indonesia consumed more than any other sectors

Introduction Why should we focus on building envelopes?  Building envelopes contribute more than 60% compare to other part in the building  Building envelopes are more adjustable compared to the structure  Building envelopes can be dismantled or changed easily  Building envelopes is the biggest contributors for the cooling load

Introduction Building with 50% void can be:  Reduced the latent and internal load  But increasing the perimeter load Variable to reduce the perimeter load  Building orientation  Material chosen  Design Hirano et al, 2004

Methodology Electricity used - household energy audit Energy use data collection – process analysis (cradle to gate) quarrytransport manufactureconstruction

Methodology  Life cycle energy from cradle to gate –Raw material extraction –Production –Construction –Occupation phase  Investigation and open interview for acquiring data from factories and construction site  Direct and indirect questionnaire to obtain data from household  Focused on two similar house with different enclosure materials

Methodology  Life Cycle Energy (LCE) where: –LCE= Life-cycle energy –EEi= Initial embodied energy of enclosure material –EErec= the recurrent embodied energy (maintenance) –OE= the total annual operational energy (cooling load) –Year= Building lifetime

Case Study Similarity  Landed house in Semarang  Gable roof  55 m 2 total floor area  Air conditioned at 2 bed rooms and non A/C at living room  Similar occupation behaviors  m’ fenestration  Facing north  Both has the same building structure and other finishing material (ceramics and wall paints)

Case Study HOUSE 1  Concrete roof  Concrete block walls  Steel roof frame  Gypsum ceiling (3mm)  Clear glass (2mm)  Aluminum frame windows and doors HOUSE 2  Clay roof  Bricks walls  Steel roof frame  Gypsum ceiling (3mm)  Clear glass (2mm)  Aluminum frame windows and doors

Result  Material Embodied Energy * reference sources

Result  Embodied Energy

Result  Energy used

Result  LCE for HOUSE 1

Result  LCE for HOUSE 2

Result  The emergy percentage at total LCE

Conclusion  Cement based material consumes more energy during production compared to the clay based material  By using clay based material instead of cement base for enclosure will safe 6,400 MJ during production and 124,600 MJ during its occupation phase for 20 years scenario in single landed house  Using clay based material for enclosure at residential sectors in this regions (Semarang, approx 1,4 mil inhabitant) will safe more than 86,400 GJ

Conclusion  High thermal resistance material is more preferable for tropical weather  Clay based material have higher R-value than concrete based material and therefore more thermal resistance  Reduction in perimeter load in tropical country has significant effect on the overall energy requirement as compared to internal and latent load