A New Approach to Studying Traditional Roof Behaviour in a Changing Climate—A Case Study from the Mediterranean Island of Malta

JoAnn Cassar,Elizabeth Muscat Azzopardi,Charles Galdies

doi:10.3390/heritage4040196

Abstract

The behaviour of traditional roofs affects issues relating to sustainability, zero-carbon targets, and Urban Heat Island (UHI) effect. This paper discusses an innovative approach towards understanding the behaviour of porous, and other types, of roofs in Malta in relation to temperature and moisture characteristics, and to project this behaviour onto a changing climate, predicted to be hotter and drier. The new methodology is being trialled on four roof types, on historic buildings, the innovation being the use of data from co-temporal Earth Observations (EO) and Unmanned Aerial Vehicles (UAVs), in conjunction with in-situ data. This research is helping to develop a new application for Remote Sensing in Cultural Heritage; results should enable recommendations for sustainable use of traditional roof-building techniques. The initial results show that the traditional roof has different (reflective and emissive) properties from the hybrid roof, that are being detected from space, complemented with UAV, hand-held thermal camera and in-situ measurements. These results are preliminary; satellite images for spring/early summer and mid-summer and the corresponding UAV images are expected to provide more conclusive information. These promising results should enable the proof-of-concept to progress onto a larger number and greater variety of roof types, even in other Mediterranean countries.

Highlights

The Maltese Islands in the Central Mediterranean have always had a plentiful supply of good building limestone, from which all of Malta’s traditional and historic buildings over hundreds of years have been built [1,2]
What follows are some of the results presented in a systematic way, exploring first the thermal situation in the surrounding areas and utilising the data gathered by the different techniques to zoom in gradually onto the target roofs, until the in-situ data from the roofs is presented
The uniqueness here is that these tools are being deployed for the monitoring of roofs and extraction of thermal and moisture data, to enhance conservation and use of historic building in a sustainable and energy-efficient manner whilst projecting this understanding into the future scenario of climate change

Summary

Introduction

The Maltese Islands in the Central Mediterranean have always had a plentiful supply of good building limestone, from which all of Malta’s traditional and historic buildings over hundreds of years have been built [1,2]. This paper focuses on the roofing, including materials and mode of construction, which have allowed for these roofs to protect from water ingress, and (because of the ubiquitous slight slope of these roofs) to act as a “channel” for the collection of precious rainwater in an otherwise semi-arid environment, and its direction to underground cisterns, as storage for future use [5]. Studying their behaviour in an innovative manner can help promote their continued use, even by recommending improvements, and possibly extending their application to other non-traditional buildings. These have provided the baseline methodology for this study, which has included other more advanced monitoring technologies, including simultaneous thermal and other EO data, for the first time resulting in an altogether innovative methodology

Objectives

Methods

Results

Discussion

Conclusion