Study of the green building implementation: towards net zero energy housing (case study: South Tangerang)

The study investigates the use of green building concepts by private developers in South Tangerang. The implementation of green building policies has a significant impact on the government’s target of reducing energy consumption and carbon emissions by 2030. The private sector, specifically large private developers in South Tangerang, has made significant contributions to the successful implementation of green building. The majority of new houses built in recent years have been built by large private developers with a lot of land in South Tangerang. This research is significant because a large developer with all of the financial and technical resources can be a pioneer in the future application of green building for residential homes. For governments with all financial and technical constraints, the active role of private developers will greatly aid in the mass implementation of green buildings. However, the constraints and challenges faced by private developers in incorporating green building concepts into their products remain poorly understood and discussed. A simulation of a typical model house built by a private developer can be used to assess the private sector’s potential for energy and economic savings. There are still very few green building discussions that address the potential of housing to save energy. The study is expected to contribute to discussions about green building applications by providing an overview of the challenges and potential for implementation.


Introduction
Indonesia, as a country with a large population of more than 265 million people, an economy that continues to grow and is the largest in Southeast Asia, has experienced a rapid increase in GDP over the last two decades [1].Stable economic growth contributed to doubling electricity consumption from 129 TWh 1 in 2008 to 256 TWh in 2018 [2].The pattern of household energy consumption tends to increase in tandem with an increase in income, which is marked by non-food consumption such as electronic equipment and food.Household energy consumption is also being influenced by various factors such as advances in information technology and demographic transitions.This increase in energy consumption, along with population growth and economic activity, will eventually increase demand for fossil-based energy.As a result, innovation from renewable energy sources is required, saving both energy consumption and using energy-efficient electronic devices [3].
The housing sector consumes nearly 40% of all electrical energy, followed by industry (37%), commercial (23%), and transportation (0.11%) (Ministry of Energy and Mineral Resources, 2018).Meanwhile, electricity in Indonesia is still primarily supplied by coal (58%), natural gas (27%), and petroleum (6%), with renewable energy (water, solar, geothermal, and wind) accounting for only 8% of IOP Publishing doi:10.1088/1755-1315/1351/1/012016 2 total national energy consumption [4].As a signatory to the Paris Agreement, Indonesia has committed to reducing greenhouse gas (GHG) emissions by 29% below baseline business as usual (BAU) in 2030, or 38% below baseline BAU in 2030 with international support.To meet this goal, the government must encourage a 19% to 24% reduction in energy consumption below BAU [2].The fluctuation in energy prices, particularly for oil and natural gas, over the last year as a result of the Covid-19 pandemic and global geopolitical problems has forced many countries to reconsider their energy security strategy and, as soon as possible, convert from fossil fuels to renewable materials while also increasing energy efficiency.
So far, the concept of green building has not become a trend in residential building planning and design.The general perception of green home design is that it is an expensive alternative to traditional home designs.This is exacerbated by the price of electricity per Kwh2 in Indonesia, which remains relatively low in comparison to other countries because some of it is still subsidized by the government (esdm.go.id).This is also due to a lack of public awareness that energy-efficient home designs can be a future investment in which residents can live in buildings with net zero energy and zero emissions.The initial investment in solar panels and other components will be offset by significantly lower house operating costs when compared to conventional houses.It is necessary to increase understanding of the concept of passive design in order to reduce energy consumption, and private developers can serve as role models in designing housing models that use passive design.The Green Building Council Indonesia / GBCI (2014) criteria will be used in the assessment of the houses studied, namely energy efficiency & conversion, material sources & cycles, indoor health & comfort, land use efficiency, building environmental management, and water conservation.
Green building research is critical given the threat of climate change and the possibility of an energy crisis in the future.As a result, both the supply and demand sides must be regulated in this manner.The Indonesian government has set targets to be met by 2030, which are outlined in Ministerial Regulations and local regulation (Peraturan Daerah/Perda), but implementation and progress have been slow in the last decade.Several cities, including Jakarta, Bandung, Semarang, and Bali, have also issued Governor Regulations governing the implementation of green buildings, with the goal of having more than 60% of buildings in Jakarta certified as green.This study focuses on several issues, such as: • What the typical electrical energy consumption of medium-sized building constructed by a private developer?• How to design residential house models built by private developers to meet green building standards?
There is still little research focused on building houses related to the use of green building and how large its potential is.Private developers, on the other hand, dominate the construction of new houses in the Jakarta Metropolitan Area (JMA), particularly in South Tangerang.As a result, private developers' role and influence in popularizing green building is critical.In recent years, several developers have begun to incorporate the concept of green building into the sale of their home products, and the market has shown to respond favourably.However, there are still many obstacles and challenges from unaddressed policies, so many private developers are still hesitant to incorporate the green building concept in building and marketing their home products.This study attempts to fill a void in the discussion of green building implementation in housing.

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South Tangerang: The Supporting City of Jakarta South Tangerang has become a unique case study because the area has been rapidly developed as a 'residence city' in recent years.Private developers have built many new towns to accommodate residential demand as the development of DKI Jakarta's urban areas has spread to its surrounding cities such as Bekasi, Bogor, Depok, Tangerang, and South Tangerang.Because of affordability and environmental concerns, many young professionals have chosen Tangerang and South Tangerang as their first choice for residency.It is not surprising that the population of South Tangerang has increased in recent years, rising from 1,365 million in 2021 to 1,378 million in 2022, a 0.94 percent increase [5].South Tangerang is divided into seven districts (kecamatan): Ciputat, Pamulang, Pondok Aren, Pondok Ranji, Sawah Baru, Setu, and Serpong Utara.

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In comparison to other cities, South Tangerang has a massive residential land area of around 108,4 km2 of total area of 164,86 km2 (65% of South Tangerang total area) [6].The private sector builds the majority of housing.For example, in 2018, the private sector built approximately 447.364 units, while the government built 161.299 units [7].Big developers are competing in South Tangerang to build housing for middle-and upper-income households.Massive townships in South Tangerang such as Bintaro, Alam Sutera, and BSD City have been popular among professionals working in Jakarta who are looking for a more affordable and higher quality of life.To meet housing demand, these developers sell hundreds of thousands of units each year.They must compete with other large township developments in Tangerang Regency such as Summarecon Serpong, Lippo Karawaci, and Citra Raya.As a result, the private sector develops not only housing areas but also business and commercial districts in their township development.These projects maintain their independence from the urbanization processes that surround them by including self-contained infrastructure [8].
These large private developers have the potential to be leaders in the use of a sustainable approach to urban development in our city.For example, almost all of the housing developed by these developers has access to pipe water, as opposed to the densely populated areas of Jakarta, where only 64% of DKI Jakarta's residents have access to pipe water [9].Many Jakarta residents rely on groundwater, which has resulted in excessive groundwater extraction, exacerbating the problem of land subsidence [10].With all of the financial and technical resources that these private developers have, it is possible that the application of sustainability in general, and green building in particular, can be accelerated.

Methodology
Research can be divided into 2 stages, which will be carried out to obtain results that can answer research questions.In the first stage, researchers conduct a literature review and simulation of one of the houses developed by a private developer, with the condition that the house is landed, 120-150 m2 in area, two levels, built within the last 5 years, 2200 VA electricity (non-subsidized electricity consumers) which is the main model used marketed by the developer, to be used as baseline data for home energy consumption which will later be compared with home models with a green building concept with the same criteria in green building and modelling software such as EDGE app.The EDGE app was chosen because it is simpler than other green building software such as Energy Plus and Autodesk Ecotect Analysis.It is also free and does not require installation because it uses a cloud system in the process.
Nonetheless, the software has a limitation in that the data used cannot be specific to the research location but rather to the nearest city or area.Furthermore, the software cannot simulate to the level of detail that other software can.However, the authors believe that the software is more than adequate for calculating the efficiency of a house or building.The software can also assist designers or architects in the early stages of the design process in selecting design strategies to achieve building efficiency.The second stage involves conducting an in-depth interview with Green Building Experts about the development of energy-efficient building concepts and challenges in implementation and policies.
After the data in the form of interview and simulation results were obtained, transcripts and analysis were carried out to get the connection of the research.It is hoped that through premier and secondary data, this study can explain the energy consumption of a typical model house built by a large developer with the potential for efficiency that can be realized if it is designed with a green building concept.All measurements follow the grading guidelines issued by GBCI for green building certification.The authors do not specify the type of housing or the developer, instead focusing on a unit that can represent a house design that many developers in South Tangerang have built.

The Baseline: Developer Conventional Design Assessment
To answer the research questions, the authors simulate one of the houses built by a private developer, with the criteria of a landed house, area of 120-150 m2, two levels, built within the last 5 years, 2200 VA electricity (non-subsidized consumer electricity), which is the developer's main model marketed, to be used as baseline data.Energy efficiency will be compared later in the Edge App to determine how much energy can be saved by adjusting to a green building design approach.EDGE (Excellence in Design for Greater Efficiencies) is a green building standards and certification system developed by the International Finance Corporation (IFC), a member of the World Bank Group, to assist in determining the most cost-effective options for designing green buildings in the context of the local climate.EDGE can be used in all types of buildings, including new construction, existing structures, and major renovations (Salsabila & Prianto, 2020).The building is evaluated by EDGE based on three criteria: energy efficiency, water efficiency, and material efficiency.
This study employs a model of a typical house for middle-and upper-income households in one of South Tangerang's private developers (please see Fig. 1.1).Nonetheless, the study is not intended to compare a model designed by one developer to models designed by other developers.The study is based on independent variables, which are not compared or linked to other variables.In order to qualify for EDGE certification, buildings must save 20% on energy, 20% on water, and 20% on material energy emissions when compared to conventional buildings.The software will calculate parameters such as layout, orientation, shading, ventilation, structural systems, and material specifications etc.

Figure 1. Typical design model of a middle-and high-income house built by developers in South Tangerang
The case study is a typical conventional design by a private developer would be two stories with one elevation facing the road and one or two cars in a carport.The first floor houses the living room, the toilet, the kitchen, the domestic worker room, the warehouse room, and the service room.The second floor houses the master bedroom, children's room, bathroom, and workroom.The house faces south and has a floor area of approximately 167 m2.According to EDGE software, the building saved 10.22% on energy (Please see Fig 2).This energy efficiency was obtained from a WWR (Window Wall Ratio) of 29,1% versus a baseline (typical building in the area) of 44%, roof insulation with a U-value of 2 W/m2K versus a baseline of 2.15 W/m2K, and cooling system efficiency with a COP of 2.8 versus a baseline of 3.16.Furthermore, the use of efficient lighting for both outdoor and indoor use contributes to the case study's energy savings.

Figure 2. The software EDGE calculation on the energy efficiency of the house
In terms of water, water efficiency measures around 28.95% higher than average housing (please see Fig 3).It appears that using water-efficient toilet and kitchen faucets, showerheads, and efficient water closets for all bathrooms (6 L/high volume flush and 3 L/low volume flush) has proven effective in reducing water consumption.Nonetheless, the water recycling system in the case study house has not been implemented to reduce additional water consumption because the house was not designed with a green building approach.In terms of material energy emissions, the case study home is only 1% more than average housing.It appears that the developer is still unconcerned about embodied energy in material savings (%) or total annual CO2.The use of recyclable materials was also not seen in the case study house.The overwhelming majority of Indonesian developers prioritize price and affordability over sustainability concerns.Analysis: Simulation the potential on energy saving, water saving and material saving Based on the baseline performance, the case study house performs reasonably well in terms of energy efficiency, water efficiency, and material efficiency.In fact, the house case study has already met the 20% water efficiency target required to obtain an EDGE certificate.Thus, it demonstrates that some new housing built by private developers has the potential to raise its level to obtain a green certificate, at the very least an EDGE certificate.The authors then conduct some experiments to determine the formula for increasing efficiency in order to obtain the EDGE certificate standard of 20% on energy, 20% on water, and 20% on embodied energy material.The authors also consider the least expensive options for increasing building performance, which is critical for most developers who want to keep the initial cost of their house products low.
The initial simulation results for the energy category yielded a value of 10.22%, which falls short of the EDGE standard's minimum target of 20% efficiency.The energy conservation strategy used in the case study object's existing building yielded a value of 10.22%.Some of the strategies that have been implemented include increasing the window to wall ratio to 29.1% (EEM01 Window to Wall Ratio), using roof insulation (EEM05 Roof Insulation), using energy efficient AC (EEM13 Cooling System Efficiency), and using cost-effective LED lights.Energy for indoor and outdoor areas (EEM22 Efficient Lighting for Internal Areas, EEM23 Efficient Lighting for External Areas), lighting settings using timer and dimmer technology (EEM24 Lighting Controls), and energy-saving refrigerators and washing machines (EEM29 Efficient Refrigerators and Clothes Washing Machine).Furthermore, to achieve 20% energy efficiency, optimization or improvements, such as the use of roofing materials/roof coatings or reflective paint (EEMO2 Reflective Roof), can be carried out.This also applies to external walls, where reflective wall materials/coatings or paint are used (EEM03 Exterior Wall).Aside from that, one strategy that can be used is to switch to glass that has a lower heat conduction value (EEM09 Efficiency of Glass).By combining the three optimization strategies mentioned above, the energy efficiency value for the case study building can be increased from 10.22% to 25.99%, allowing it to meet the EDGE standard for energy efficiency in green buildings.The water efficiency value obtained for the case study object from the initial simulation based on existing data was 28.95%.This value meets the EDGE standard for water efficiency, which is greater than 20%, so the researchers did not optimize further in this category.The 28.95% value was obtained through a combination of water-saving strategies, specifically saving water from sanitary uses (WEM01 Water Efficient Showerhead, WEM02 Water Efficient Faucets for All Bathrooms, WEM04 Efficient Water Closets for All Bathrooms, and WEM08 Water Efficient Faucets for Kitchen Sinks).A smart water meter is also used to measure water consumption in the case study object building, which aids in water conservation efforts (WEM17 Smart Meter for Water).
The material efficiency category receives the lowest value during the simulation by entering existing data into the EDGE App, receiving only 1% of the standard required to obtain EDGE Green building certification, namely 20%.This is due to the fact that the majority of the materials and construction procedures for the case study objects use conventional materials that are commonly used in residential building construction processes, so the material efficiency values are nearly identical to the material efficiency of the EDGE App's base case building.The material aspect optimization includes two components: the addition of Pulverised Fuel Ash (PFA) material, also known as Fly Ash, as a mixture of concrete materials used for bottom floor construction (MEM01) and intermediate floor construction (MEM02).The material used is concrete slab in situ reinforced slab with more than 30% PFA.Based on these two material efficiency optimizations, a value of 29% was obtained, which meets the EDGE standard building requirements of greater than 20% (Please see Fig. 5 & Fig. 6).on building performance.The simulation also calculated the typical electrical energy consumption of a medium-sized building constructed by a private developer, with the air conditioning taking the most consumption.Private developers may be aware of green building issues, but they may not prioritize them because the consumer market is still small.Several studies have found that green buildings are only 5-15% more expensive than conventional buildings [11].Construction costs are approximately 12.5% higher for net zero buildings [12].Green buildings that are LEED (United States Green Building Agency) Platinum certified cost 7.6 -10.3% more than conventional buildings [13].The costs will be much lower if the certificates targeted are gold and silver certificates.Furthermore, even for small private developers, EDGE certification is relatively inexpensive.
The implementation of policies requiring the implementation of green buildings, on the one hand, is very effective in encouraging changes toward more energy efficient and environmentally friendly buildings, but on the other hand, it will cause less interest for private parties to enter real estate, potentially reducing the supply of new buildings in Indonesia's major cities.Even though providing incentives, as done in several countries, is successful, it requires large sums of money and its long-term viability is still in doubt.As a result, the authors contend that the market has become the deciding factor for the private sector to invest in green building.The government must support the market in order to provide a more sustainable approach.

Figure 3 .
Figure 3.The software EDGE calculation on the water efficiency of the house

Figure 4 .
Figure 4.The software EDGE calculation on the case study house's improved energy efficiency

Figure 5 .Figure 6 .
Figure 5.The software EDGE calculation on the case study house's improved material efficiency