The Implications of Future Wind-Driven Rain Exposure on the Hygrothermal Performance of Internally Insulated Solid Walls in London

Jacqueline Lu,Hector Altamirano,Valentina Marincioni,Scott Allan Orr

doi:10.14293/icmb210038

Abstract

<p class="first" id="d7810290e76">With approximately 40% of the London building stock built before 1919, internal wall insulation (IWI) is one of the likely measures for deep retrofit to meet carbon emissions targets. However, IWI can lead to moisture accumulation and associated unintended consequences, especially in walls highly exposed to wind-driven rain (WDR). Climate change is predicted to exacerbate WDR exposure. This paper presents a comparative analysis between the hygrothermal performance of IWI under current and far future (2080) climates. Historic weather station data and UKCP18 climate projections were used to develop weather files for simulating current and future climate, respectively. Hygrothermal simulations were performed using DELPHIN. Assemblies include calcium silicate, phenolic foam, and wood fibre systems. Future climate predictions are associated with a rise of interstitial relative humidity, leading to patterns more favourable to mould growth.

Highlights

Peer-review under the responsibility of the organizing committee of the ICMB21
In line with BS EN 15026 [5], simulations under current climate conditions and a far (i.e. 2080) future climate used the year with 90th percentile rainfall
A comparative analysis concerning interstitial temperature and relative humidity between existing brick and insulation was carried out to evaluate the influence of future climate on interstitial condensation and mould growth risk

Summary

Introduction

With approximately 40% of the London building stock built prior to 1919, reaching net-zero carbon emissions in refurbishments will likely require internal wall insulation (IWI) where exterior alterations are limited by aesthetic preference or conservation principles. IWI will improve thermal performance, but it will alter hygrothermal behaviour: introducing extra vapour and thermal resistance reduces inward drying and poses a risk for interstitial condensation. The changing climate will present more challenging environmental loads experienced by external walls with a major one being wind-driven rain (WDR), which has been studied to be the most critical to moisture risk [1]. The aim of this paper is to understand current and future WDR exposure in London and analyse moisture behaviour within internally insulated solid walls

Objectives

Methods

Results

Conclusion