The importance of thermal modelling and prototyping in shelter design

ABSTRACT

More than 9 million people live in shelters globally, often in extremely hot climates. The thermal performance of shelters is often overlooked in the design process, despite being a consideration second only to safety in surveys of camp dwellers. Indeed, indoor temperatures exceeding 40°C have been recorded in previous studies. To aid in improving conditions, the roles building simulation and prototyping could play in forecasting shelter thermal performance as part of a new shelter design process are examined. The thermal performance of prototypes, built in the refugee camp of Azraq, was monitored during the hot season to evaluate four design approaches: (1) “blind” (uncalibrated) models, (2) calibrated models, (3) on-site design-variants and (4) off-site prototypes. These included the original shelter and six design alternatives implementing different overheating countermeasures. The results demonstrate that blind models are sensitive to the judgement of uncertainties but were still qualitatively useful. Model calibration vastly improves the agreement and significantly enhances forecasts of performance for the design alternatives, which remained similar across examined climates. It is therefore concluded that simulation and prototyping, either on-site or off-site, should be adopted within the shelter design process before mass deployment, to create better-living conditions for their dwellers.

KEYWORDS:

• Shelter
• design
• prototypes
• overheating
• building simulation
• calibration

Acknowledgements

This research was conducted thanks to the collaboration of the UNHCR and the NRC. Authors particularly thank Vincent Dupin and Alaa Amoush from UNHCR for facilitating the construction of the shelters and experiments, and the support of Omar Bani-Ahmad Otum from Princess Sumaya University for Technology. The authors also express their gratitude to all those involved in its construction and setup, specially to Ayoub Ibrahim Al Samawi, Luay Ali Albrek and Natalia Paszkiewicz. This research was possible thanks to cited open source software and the communities behind them.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data access statement

Data presented in this study are openly available at https://doi.org/10.15125/BATH-00668 (Fosas, Moran, Natarajan, Orr, & Coley, 2019).

ORCID

Daniel Fosas http://orcid.org/0000-0001-8407-3431

Sukumar Natarajan http://orcid.org/0000-0001-5831-1678

John Orr http://orcid.org/0000-0003-2687-6353

David Coley http://orcid.org/0000-0001-5744-1809

Notes

1 Authors’ estimate from the 8.7 million living in shelters by the end of 2016 (UNHCR, 2017b) and the 0.8 million that arrived since to Bangladeshi camps as of May 2019 (UNHCR, 2019a).

2 The reasons for the good agreement are that Azraq is in the middle of a geographically homogeneous area that is flat, far from large bodies of water and with a high frequency of clear sky days (Fosas et al., 2018b).

3 These values are representative of the performance of the calibrated simulation for both the validation and the complete period of the experiment. The shelter remained completely closed except for the vents until the 17th of September, causing a wider variability in the performance of the simulations. This causes metrics for the validation period to outperform those of the training – and hence those of the complete period as well. Here, it was opted to report the maximum absolute values.

4 It must also be noted that, in this experiment, design alternatives are implemented retrofitting existing shelters. Although some strategies would have delivered increased airtightness (increased insulation, increased thermal mass by cavity fill), having to disassemble the envelope and re-drill the IBR panels to the structure likely had the opposite effect.

Additional information

Funding

This research was funded by the EPSRC ‘Healthy Housing for the Displaced’ project [grant number EP/P029175/1]. Daniel Fosas appreciates the support of the EPSRC Centre for Doctoral Training in the Decarbonisation of the Built Environment [grant number EP/L016869/1] and the “la Caixa” Foundation.