Climate-resilient Redesign of a Residential Project in Debrecen through Functional Diversification: A Performance-based Study on Water-Carbon Balance and UHI Mitigation

Abstract

The paper discusses the Tócóvölgy residential development project in Debrecen, Hungary, to consider the challenges of adaptation in suburban residential areas due to climate change, particularly heatwave, extreme precipitation within a brief period, water resources management, and low-carbon mode of operation. The original design was mostly residential and large-scale landscape water bodies, but it did not have enough functional integration, significant maintenance loads on open water systems, and vague relationship between the roof system and water-heat-carbon goals. In the context of the same site limits and similar residential size, the research compares the original design with the new design. The methods used to evaluate the designs are area statistics, runoff coefficient method, comparison of stormwater retention capacity under a typical storm scenario, reference evapotranspiration estimation, solar radiation analysis and incremental carbon budget method. The findings show that the proposed design increases the non-residential functional area by approximately 46.16%, decreases the area of hard surfaces/roads by roughly 33%, and increases blue-green space by about 6.1%, while the blue-green space is increased by about 6.1 percent. In the chosen 10-minutes, 107.46 mm/h storm condition, green roofs and landscaped balconies decrease runoff by about 458.91 m³ in comparison with hardened control condition. After considering the storage capacity of the lake and grass-lined swales, the residual flood volume is 0 m³ within the defined storm scenario. The graywater irrigation coverage rate of rooftop green spaces is about 414.8 percent. The average solar radiation in summer declined by about 33.21-37.20 percent and the average solar radiation in the heating season reduced by about 27.66 percent which stands for a trade-off between summer cooling and winter solar gain. Within the defined incremental carbon boundary and 50-year study period, the new design shows incremental carbon-neutrality potential, with a cumulative net carbon effect of -745.6 tCO₂e. However, the carbon-neutrality margin is narrow, and the result depends strongly on long-term PV performance, cooling-energy savings, and the control of additional winter heating demand. Overall, the new plan has the potential of incremental carbon neutrality within the stated limits and may boost the climate resilience of the residential area with the help of functional integration, decentralized stormwater management, non-potable water recycling, rooftop energy systems, and multi-tiered greening.