Climate-resilient Urban Neighborhoods: Assessment of Urban Densification Scenarios in the Extreme Climate events

Abstract

Growing population in Swedish cities and limited natural resources combined with climate change impacts led decision-makers to develop densification strategies in city planning. However, densification could come with several challenges including reduced green spaces, increased urban heat island effect and energy demand, as well as the lack of thermal comfort in buildings. Densification becomes even more challenging when considering the projected increase in the intensity and frequency of extreme climate events, such as heatwaves and cold snaps. In this study, seven densification scenarios (L shaped, O shaped buildings) based on the trade-offs between urban greenery (L-U-O shaped with green) and urban density (moderate, and high density) were developed considering the number of floors and urban streets. Using a real urban area in Stockholm as a case study (base case), the measures included modifications to existing buildings (considering building age, physical properties) and the addition of new constructions in open spaces. Furthermore, to evaluate their impact on the energy performance of urban neighbourhoods in Stockholm, the energy performance and indoor thermal comfort of the developed scenarios were assessed. The assessment was done against historical climate conditions using the Typical Meteorological Year (TMY) weather file and future climate data targeting 2069. Three future climate weather files covering typical and extreme conditions were synthesized (2040-2069), including Typical Downscaling Year (TDY), Extreme Warm Year (EWY), and Extreme Cold Year (ECY). The dynamic energy simulations were conducted using the EnergyPlus engine, and the building properties were retrieved from open-source GIS databases, and Swedish building codes. Existing buildings were grouped as construction before and after 1975 and 2000. Results show that extreme weather conditions have a significant impact on energy performance of buildings, indicating the importance of considering extreme climate conditions in conventional urban planning practices. Increasing urban density from 0,40 to 0,52 led to 18% drop in heating demand in comparison to base cases. Adding 22% green surface coverage had minimal impact on heating and cooling demand under moderate densification in all weather conditions except for heating demand in extreme cold years. Higher green area density led to cooling demand to reduce by 35% during EWY in high densification scenario. Finally, the advantages and disadvantages of various design solutions, measures, and densification scenarios were evaluated. The findings of this study can support more informed decision-making for architects, urban planners, and city authorities regarding densification strategies.

Popular Abstract

Swedish urban planning was influenced by industrialization, introducing the “Stenhouse” building type—medium-height buildings arranged in rows with compact inner courtyards. Over time, building heights decreased while green spaces became more integrated, shaped by the garden city movement. Later, the functionalist era encouraged high-rise construction to minimize land use by building vertically, aiming to preserve the natural environment. Throughout years with changes in urban planning, majority of people moved to cities and in Sweden 88% of the population, has been living in cities. Agricultural land is limited, which cannot meet with growing demand of urbanization and farming. Also, warmer and rainy future weather conditions with climate change need attention. Densification of urban areas is in the agenda, which comes with problems such as heat island effect, reduced green areas and increasing indoor temperatures. Therefore, climate change projections, especially rising rainfall intensity, now demand new considerations for urban design.
To respond to these challenges, densification scenarios were developed and analyzed using 30 years of projected weather data (2040–2069) and 15 years of historical data. A real urban district in Stockholm served as the case study (base case), where existing structures were modified based on their age and physical characteristics, and new buildings were proposed for currently open areas. Scenarios varied in building shapes (L, U, I, O), heights (up to 17 floors), street widths (7m and 10m), and green surface coverage (22%).
Seven densification scenarios were created with historical and projected weather data for 2040–2069, including extreme cold and warm years To assess the impact of these scenarios on the energy performance of urban neighborhoods in Stockholm, both energy efficiency and indoor thermal comfort were analyzed. The evaluation used historical weather data from the Typical Meteorological Year (TMY) as well as future climate projections for 2050. These projections included three synthesized weather files representing typical and extreme future conditions between 2040 and 2069: the Typical Downscaling Year (TDY), the Extreme Warm Year (EWY), and the Extreme Cold Year (ECY). Dynamic energy simulations were performed using the EnergyPlus engine. Building data was sourced from open-access GIS databases and Swedish building regulations. Existing structures were categorized based on construction periods: pre-1975, 1975–2000, and post-2000.
Findings showed that increasing density and building height reduced heating demand by up to 18%, while adding green space in high-density areas halved heating demand in Extreme Cold Years but slightly increased cooling demand. In Extreme Warm Years, greenery helped reduce cooling demand by up to 58%. An H/W ratio of at least 3 was essential to reduce cooling demand and urban heat island effects. L-shaped buildings gained the most from greening, while U-shaped buildings saw moderate benefits. The most energy-efficient configurations were 17-floor O-shaped buildings in high-density layouts, while 5-floor L-shaped buildings in moderate density had the highest energy use intensity (EUI). Narrower streets (7 meters) with taller buildings reduced heating demand by 48% but raised cooling needs.
The study concludes that future urban plans must factor in extreme climate scenarios. Densification with the right balance of height, form, street width, and green space can reduce energy use. However, overheating remains a challenge, especially in dense urban environments, indicating the need for integrated, climate-adaptive design strategies. Also, planners should consider that green space had a limited impact in moderate-density areas and was less effective at mitigating overheating in dense developments.

• author: Turk, Suheyla
• supervisor: Kavan Javanroodi
• organization: Division of Energy and Building Design
• course: AEBM01 20241
• year: 2025
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: Extreme climate events, urban densification, heating and cooling demand, urban microclimate, urban greenery
• language: English
• id: 9187359
• date added to LUP: 2025-06-13 12:41:51
• date last changed: 2025-06-13 12:41:51