By Ruth Erlbeck and Ralph Trosse
The “Urban Nexus” is the theoretical and technical approach of a regional GIZ project for integrated resource management, financed by the Federal German Ministry for Economic Cooperation and Development (BMZ) and implemented in South and Southeast Asia. This article explains how it works.
The urban nexus concentrates on the sectors of water, energy and food security, as these are the sectors that will reach significant scarcity of up to 50% by 2030 at the latest if existing consumption and production patterns remain predominant. The Nexus approach introduces integrated, cross-sectoral planning, management and implementation as the leading principle to overcome mono-sectoral planning in urban development and infrastructure projects. Thereby, the approach aims to avoid silo thinking. Synergies between water, energy, and food security should be considered and promoted to make optimal use of these scarce natural resources, thus creating resilient cities.
GIZ’s Nexus Project focuses on two aspects: For one, it deals with the “hardware” aspect of resilience, introducing innovative and environmentally friendly engineering solutions to improve the physical infrastructure of cities. On the other hand, it also engages with the social aspect (“software”) of resilience by promoting people-centered development (“leave nobody behind”).
In order to promote multi-sectoral planning, Nexus Task Forces have been created in Nexus cities by resolution of their mayors. They are preparing future innovative and cross-sectoral infrastructure projects within these cities. For example, a new low-cost housing project for informal settlers of Santa Rosa Municipality in the Philippines was prepared in a multi-sectoral manner. Thanks to the Nexus Task Force handling the project, social, financial and infrastructure development aspects were simultaneously taken into consideration. In Da Nang in Vietnam, a waste water project was elaborated by the Nexus Tasks Force that works towards water reuse, energy generation and nutrients for (urban) agriculture.
Climate change resilient pilot housing in the Philippines for half the market price
Housing schemes are ideal projects, as they require coordinated, cross-sectoral efforts for infrastructure provision in coordination with different stakeholders and consultation with the beneficiaries to create resilient buildings. Hence, the Nexus Project collaborated with the Bicol College for Applied Science and Technology (BISCAST) in Naga City in order to design and built a low-cost and climate change resilient pilot house. This pilot house was inaugurated at BISCAST on June 24, 2016.
The pilot house represents an alternative to conventional construction of affordable, social housing. Low-cost housing technology including climate-adapted and energy efficient devices was applied in its construction. This is particularly relevant in a country like the Philippines, which is increasingly and frequently exposed to natural disasters such as hurricanes, earthquakes and floods. Resilient and cost-efficient housing is therefore the most urgent need. With 10% of the population of 100 million living below the poverty line social housing becomes an even more pressing issue.
The pilot house (71 m2) costs less than 9,225 PHP (195.80 USD) per square meter. This makes it half as expensive as conventional social and affordable housing, where prices amount to up to 20,000 PHP (424.51 USD) per square meter. Without the cost for finishing work (tiling, flooring, plastering, painting, etc.), the price can even be lowered to PHP 5,500/m2 (113.88 USD), leaving the finishing works to be done by the owners in order to make it affordable for lower income groups.
Moreover, the house was built with environmentally friendly construction technologies (prefabricated beams and hollow blocks) and without wooden formwork. It can be built in a short span of time, hence reducing even more costs.
The specific advantages of the applied technology consist of:
- Modular architectural system reducing the number of different building parts, leading to a reduction of different types of formwork
- Reduction of waste material and waste water on site by up to 30%
- Approximately 50% reduction of mortar due to the hollow concrete blocks (HCB) concept of “closed bottom”. It was also introduced in Ethiopia as part of the National Low-cost Housing Program, which was initiated by GIZ. The hollow block with a “closed bottom” is now a national standard.
- Reduction of 40% of concrete and 30% of steel works for slab construction due to HCB-slab system, which is also part of Ethiopian’s National Low-cost Housing Program.
- 30% increase in the use of cement for HCB in order to achieve the required strength for load bearing walls
- Natural ventilation (cross ventilation throughout the building)
- Natural illumination, window/wall ratio 40% and roof lights
- Energy efficient devices (LED lights and occupation sensors)
- Reduction of electricity consumption by over 25% through photovoltaic system
- Water conservation via rainwater harvesting
- Re-use of clarified waste water as fertilizer for urban gardening.
The Climate Change Resilient Pilot House was built on the premises of BISCAST, since the college is a very committed partner for the dissemination of innovative technologies that are in line with the nexus approach. The young engineers and architects trained at BISCAST are the best target group to create a change of mindset. In order to achieve this goal, they are trained on-the-job together with their instructors so that they can learn directly from concrete projects. These projects are usually accompanied by contractors from the private sector who provide first-hand experiences.
The inauguration event was an eye opener to the Mayor of Naga City, who – in the course of the event – ordered his city engineers to study the technology used for building the pilot house and include it in other housing programs already budgeted and scheduled.
The representatives of the Science and Technology Commission of the Bicol Region, where the city of Naga is located, declared their full backing to introducing this innovative technology as a subject in the curricula of other colleges, and as a technology to be disseminated by private contractors. They hope to reduce construction costs, improve the stability and hence the safety of buildings.
This example shows that not only cities play an important role as key drivers of change, but that academia is another relevant partner for transformative action that reaches out to the young generation as the future of our planet.