Introduction

The climate projections established by the IPCC show a global scenario of temperature rise in Europe. Specifically, extreme heat events in the Mediterranean basin are expected to become more frequent and longer lasting. Considering this scenario, cities, homes, and their inhabitants must prepare to cope with this temperature rise and mitigate potential negative health impacts. Over the past three years, the COOLTORISE project has worked on establishing adaptation solutions for homes and neighbourhoods inhabited by populations in a situation of summer energy poverty, facing the most challenges in adapting to these high temperatures. It aims to reduce the incidence of summer energy poverty among European households by improving indoor thermal habitability conditions and reducing energy needs during the hot season. This article presents proposals made during the project for low-tech and bioclimatic solutions to adapt homes and the surrounding urban spaces, that aim to enhance resilience against extreme heat events.

Addressing summer energy poverty

Summer energy poverty is a relatively novel topic in academic literature [1] and it still lacks a clear definition and proper indicators. Further work is needed on new indicators to measure the multiple factors involved it [2]. At the European level, no definition specifically focuses on summer energy poverty, as most definitions refer to the inability to pay energy bills in general, often focusing exclusively on winter conditions. The absence of public policies focused on summer energy poverty is closely related to the lack of data for its measurement and definition [2].

While existing literature on energy poverty predominantly focused on cold climates until a few years ago, efforts over the last five years have begun to address summer energy poverty and heat issues, as seen in the  Energy Poverty Advisory Hub (EPAH) indicators. Nonetheless, a more detailed approach is needed as the gap between the analysis of winter energy poverty and summer energy poverty remains significant. This disparity reflects a historical tendency to prioritise winter energy poverty, influenced by the EU's policies and resource allocation, traditionally centred on the needs of colder regions [3]. Their focus, moreover, falls mainly on financial support for the payment of energy bills and renovation of buildings, lacking a broader and more comprehensive approach linked with summer energy poverty drivers [2].

COOLTORISE is the first European project funded by Horizon 2020 focused exclusively on summer energy poverty and aims to incorporate a broader perspective of this problem to help comprehend its multifactorial nature. The project places particular emphasis on understanding residents' behavioural patterns and adaptive capacities in coping with summer heat. This approach seeks to enhance indoor thermal comfort through cost-effective measures. Moreover, the project highlights the critical role of the urban environment in addressing this issue, proposing bioclimatic and low-tech solutions that can be easily replicated and scaled in different neighbourhoods. These interventions aim to improve outdoor thermal comfort, thereby directly enhancing conditions indoors, in order to help communities and neighbourhoods adapt to the challenges posed by summer temperatures.

Low-tech and bioclimatic solutions

COOLTORISE proposes a series of actions with households and communities to reduce energy needs and improve thermal comfort during summer. These actions include workshops to promote energy awareness, the delivery of low-cost indoor kits, and collective outdoor interventions.

1. Workshops

   To promote awareness of summer energy poverty and share strategies for heat adaptation, workshops were held in various vulnerable neighbourhoods. These workshops aimed to inform the population, among others, about the socio-economic aspects and health impacts of summer energy poverty as well as key considerations for improving thermal comfort. Additionally, the workshops sought to restore the value of heat culture, popular practices, and intergenerational learning. They also provided technical knowledge from academia to help residents adapt their homes using passive cooling strategies.

   Summer Energy Culture Workshops

   During these workshops, participants used various participatory techniques to compile both their existing strategies and those introduced during the sessions. After reviewing all the strategies, participants engaged in a discussion to evaluate each one. They then classified the strategies on cardboard into three categories, maintain, eliminate, or include.

   These strategies reviewed are classified into three scales: building scale, dwelling scale, and individual scale.

   Building Scale. Key strategies at the building scale involve various structural and exterior modifications. One crucial action is addressing insulation. Consulting different options for insulation, whether interior, exterior or within an air chamber, can significantly impact a building's thermal performance. Lightening the colour of surfaces by choosing light-coloured materials or using light-coloured paints for sun-exposed surfaces helps reduce radiation absorption. Incorporating elements that block the sun's entry, such as solar filters, curtains, and weatherstripping, can further enhance comfort. Additionally, evaluating the potential for upgrading to more efficient window and door materials is essential. Installing awnings and exterior protection elements on windows and doors can also prevent radiation from penetrating the inner layers of the house, thereby maintaining a cooler interior environment.

   Dwelling Scale. At the dwelling scale, implementing usage patterns plays a pivotal role. Encouraging cross-ventilation and ventilating during cooler times of the day are fundamental strategies. Using fans with windows closed during the hottest parts of the day helps circulate air without bringing in heat. Understanding the orientation of windows and blocking the sun's entry during hours of direct radiation is crucial. Humidifying the air by spraying curtains with water, using fans with nebulisers, and mopping the floor can enhance the cooling effect of ventilation. Controlling the operation of heat-emitting appliances by turning them off and avoiding the use of the oven further helps maintain a cooler indoor environment.

   Information is provided on the types and efficiency of air conditioning systems, emphasising the importance of minimising their use. Excessive use of air conditioning increases energy consumption and CO2 emissions, fails to protect the most vulnerable households, and contributes to the urban heat island effect.

   Individual Scale. At the individual scale, strategies focus on helping the body adapt to heat. Staying hydrated by drinking water is vital for thermal regulation, while avoiding alcoholic beverages and sugary soft drinks which dehydrate the body. Reducing sun exposure by blocking direct radiation, using sunscreen, and wearing breathable, light-coloured clothing is important. Assisting the skin's evaporation process through short, cool showers, spraying water, and using a fan can also provide relief. Maintaining proper rest and nutrition, avoiding intense physical activity, and prioritising community leisure activities that encourage socialisation contribute to overall well-being and comfort during hot weather.

   Energy bills workshops

   These workshops offered a brief overview of the energy market and utility billing, including how to read bills and practical tips for saving energy at home. Participants were also informed about additional services that might be charged, as well as the requirements for qualifying for social bonuses. Additionally, the workshops covered regulations regarding supply cuts in various scenarios.

   

   _{Figures 1 – 2: Pictures taken during workshops with Municipal Centres for Older Adults, Network of gender equality spaces, Fundación Senara and Cepaim. Source: Deliverable D3.4 – Cooltorise Project}

2. Indoor installable kits

   In conjunction with the workshops, indoor installable kits were distributed to participants. These kits contained elements designed to enhance energy efficiency and thermal comfort during the summer through passive strategies.

   Kit 1: Thermal comfort enhancement

   This kit helps to improve the feeling of thermal comfort inside the dwelling, enhancing air circulation and providing tools for immediate cooling relief. Maintaining a comfortable body temperature is crucial for overall health and well-being. This kit helps prevent heat-related issues such as heat exhaustion with the following tools:

   1. Fans: for improved air circulation and immediate cooling relief.

   2. Cooling towels: for efficient body temperature reduction.

   Kit 2: Energy and water savings

   This kit is designed to help with energy and water savings by providing practical, easy-to-implement solutions that improve efficiency. This kit includes tools aimed at minimising energy use and optimising water consumption.

   1. LED bulbs: for energy-efficient lighting as they consume significantly less energy than traditional incandescent bulbs, leading to substantial savings on the electricity bill. It also reduces heat production contributing to a cooler indoor environment and further reducing energy costs.

   2. Timer plugs: to regulate the operation of electrical appliances as it allows setting specific times for the electrical appliances to turn on and off, ensuring they are only in use when needed, leading to lower energy bills and less environmental impact.

   3. Power strips with switches for easy management: to easily turn off multiple devices at once, preventing them from consuming standby power. 

   4. Water flow reducers: for enhanced water efficiency, such as aerators for faucets and low-flow showerheads, contributes to a better water management and help lower the utility bills.

   Kit 3: Solar protection

   This kit helps prevent direct sunlight from entering the dwelling, thereby reducing thermal gains and maintaining a cooler indoor environment. It includes the following elements:

   1. Roller blinds: these are a practical solution for blocking out sunlight and significantly reducing indoor temperatures.

   2. Solar protection film: it reflects solar radiation and minimises heat gain.

   Kit 4: Efficient kitchen

   This kit is designed to optimise energy and water use in the kitchen, helping to save on utility bills while maintaining a comfortable and functional cooking environment.

   Slow cookers: this offers an energy-efficient alternative to traditional cooking methods, generating less heat and using less electricity.

   Water flow reducers: such as aerators for faucets, contribute to a better water management and help lower the utility bills.

   Kit 5: Consumption control

   This kit is designed to help the monitorisation and management of the energy use of the electrical appliances, leading to significant energy savings and improved efficiency.  

   1. Smart plugs: helps to monitor and control energy usage of connected devices remotely.

   2. Timer plugs: are an effective way to regulate the operation of electrical appliances, ensuring they are only used when needed and reducing overall energy consumption.

   These kits provide practical, low-cost, and scalable solutions for households to manage their energy consumption and improve thermal comfort, addressing both immediate cooling needs and long-term energy efficiency.

   

   _{Figures 3 – 4: Pictures taken during workshops and once the kits were prepared for each household. Source: Deliverable D3.4 – Cooltorise Project.}

3. Outdoor interventions

   Urban cooling strategies are essential for counteracting the effects of overheating and improving the energy efficiency of buildings through natural ventilation at night [2]. Two approaches were identified: passive cooling strategies in the city and urban energy simulation related to buildings [1]. The relevance of these approaches is due to inefficient and low-quality buildings and urban environments with higher UHI incidence [2].

   Taking this into consideration, the aim of the outdoor interventions in this project is to promote collective actions in private community courtyards, facilitated through a participatory process. These interventions are designed to reduce microclimatic temperatures, thereby helping households benefit from cooler surroundings and improved thermal comfort. The process was divided into several phases:

   1. Site diagnosis

      Site diagnosis is the initial step in planning an outdoor intervention, it is important to understand the site’s specific challenges and opportunities for improvement. This is done through the participation of both the community and project agents that provide guidance and technical knowledge. 

      1. Sun exposure analysis: assessing how different areas are affected by sunlight to identify hotspots.

      2. Participative board: engaging community members to gather insights and feedback derived from their own needs and experience living in the neighbourhoods.

      3. Conclusions: finally, it is important to summarise the findings to make the site diagnosis. 

   2. Co-design

      The co-design phase focuses on the collaborative development of effective passive cooling solutions tailored to the site’s needs. The process is summarised in the following steps:

      1. Propose solutions using the repository of passive cooling solutions [3] developed during the project, which offers optimised solutions that could be adapted to the specific needs of the site. Some examples are listed below: 

         • Permeable soils: using materials that allow water to penetrate, reducing heat gain from the surfaces.

         • Presence of water: incorporating drinking fountains and irrigation systems, such as diffusers to cool the environment.  

         • Presence of vegetation: planting trees and shrubs enhances shade and lowers temperatures through the natural process of evapotranspiration, where plants release moisture into the air, creating a cooler microclimate.

         • Shading: installing structures to block direct sunlight and avoid surface overheating.

         • Pavement replacement: using materials that reflect rather than absorb heat.

      2. Summary Files, documenting the proposed solutions and their expected impact. 

      3. Presentation and debate, discussing the proposed interventions with the community for feedback and refinement. 

   3. Intervention

      Finally, utilising the co-designed solution outlined earlier, a project is developed and implemented with active community participation to improve the local microclimate within the neighbourhood.

      

      _{Figures 5 – 6: Pictures taken during diagnosis and design sessions, CESAL and Vallecas interventions. Source: Deliverable D3.4 – Cooltorise Project.}

   4. Lessons learned

      Implementing outdoor thermal adaptation strategies involves recognising the time-intensive nature of these interventions. It also requires managing invisible tasks like coordinating with entities, scheduling, sourcing suppliers, and recruiting volunteers. Engaging participants through interactive materials has proven effective, treating the process like a game with boards, pens, and pictures. Other challenges include effectively engaging the community, which is often easier with established groups of neighbours. Planning activities with clear goals and providing the necessary tools is crucial. Maintaining constant feedback ensures ongoing communication and adjustments based on participant input, highlighting the importance of a structured and inclusive approach.

      Conclusions

      Addressing summer energy poverty is complex; it involves navigating multifaceted factors such as community behaviour, the built environment, and urban infrastructure. Crucially, improving urban infrastructure can mitigate summer energy poverty by reducing urban heat and enhancing indoor thermal conditions.

      The COOLTORISE project has implemented several low-tech and bioclimatic solutions tailored for vulnerable populations, significantly improving thermal comfort, as verified through implementation interviews. Reviving heat culture, traditional knowledge, and intergenerational learning are pivotal for effective adaptation.

      Nevertheless, summer energy poverty remains an underexplored phenomenon, lacking comprehensive research and data. To better address summer heat experiences and their mitigation, a better understanding of cooling strategies and measures is needed, requiring quantitative and qualitative data collection and better consideration of local microclimatic differences [4].

      References

      [1]    Bienvenido-Huertas, D., D. Sanchez-Garcia, and C. Rubio-Bellido. 2021. “Adaptive Setpoint Temperatures to Reduce the Risk of Energy Poverty? A Local Case Study in Seville.” Energy and Buildings 231: 110571. https://doi.org/10.1016/j.enbuild.2020.110571

      [2]    D. Torrego-Gómez, M. Gayoso-Heredia, P. San-Nicolás Vargas, M. Núñez-Peiró, C. Sánchez-Guevara. 2024. “Recognising summer energy poverty. Evidence from southern Europe”, Local Environ. (2024) 1–29, ene. https://doi.org/10.1080/13549839.2024.2303456

      [3]     Policy Brief No. 2 of the Cooltorise Project. “Why should we stop seeking energy savings in summer energy poverty policies? Health and thermal comfort matters”. To be published on August 31, 2024.

      [4]     Allegrini, J., V. Dorer, and J. Carmeliet. 2012. “Influence of the Urban Microclimate in Street Canyons on the Energy Demand for Space Cooling and Heating of Buildings.” Energy and Buildings 55: 823–832. https://doi.org/10.1016/j.enbuild.2012.10.013

      [5]     Sanchez-Guevara, C., M. Nunez Peiro, J. Taylor, A. Mavrogianni, and J. Neila Gonzalez. 2019. “Assessing Population Vulnerability Towards Summer Energy Poverty: Case Studies of Madrid and London.” Energy and Buildings 190:132–143. https://doi.org/10.1016/j.enbuild.2019.02.024

      [6]     Deliverable D1.4 of the Cooltorise Project “How to stay cool in summer. A collection of solutions”. May, 2022. https://cooltorise.eu/training-downloads/