Moisture Safety of Green Facades

Harry Edelman,Miia Jauni,Mihkel Kiviste,Eero Tuominen,Juha Vinha,Arto Köliö,Susanna Lehvävirta,Matti Pentti,Toni Pakkala

doi:10.30663/ay.83370

Abstract

In Nordic climate, climbers covering facades are conventionally removed, although there is no evidence of the actual impact of the climbers on the moisture performance of facades. Such information is needed to support building design and nature-based solutions for climate change adaptation. This study aimed to find evidence on the performance of green facades from the physical and life-cycle engineering perspectives of buildings by testing double-skin green facades in laboratory and field conditions. First a mature thicket creeper was grown on a steel mesh over 100 days, and it was exposed to rain and dry periods by accelerated weathering equipment in a laboratory. Then the leafless creeper was exposed to rain cycles on a rooftop in natural conditions. The results indicated the high protective capacities of the climber during the leaf season, but even during the winter season (without leaves) protective performance was measured in laboratory and natural conditions. In conclusion, double-skin green facades provide effective protection from wind-driven rain while the distance between the green structure and the load-bearing wall impacts the relative humidity levels, and the drying process of the load-bearing wall. Thus, moisture safety can be improved with a double-skin structure with ventilation and access for maintenance.

Highlights

The reduction in moisture content hinders the effects of reinforcement corrosion (Köliö et al 2016), mould or algae growth, leaching, pore filling, erosion, etc. (Neville 1995)
We present the results of laboratory experiments that simulated heavy wind-driven rain on a double-skin mock-up green facade, together with field measurements regarding the moisture balance of the facade
The amount of precipitation corresponds to a realistic weather event that may potentially occur in real-life, the objective of the study was not to mimic a specific location with distinct weather data while this would call for accounting the microclimate factors such as the impact of neighbouring buildings to wind-driven rain events

Summary

Introduction

48: 2 (2019) ss. 55–68 pockets or modules (Jim 2015a; Manso & Castro-Gomes 2015; Medl, Stangl & Florineth 2017; Mårtensson et al 2014). We use the term ‘green facades’ to describe exterior building walls covered by climbers that grow from ground-level plantings. Green roofs and facades are NBS that mitigate building-related energy consumption and greenhouse gas emissions (Besir & Cuce 2018). Most of the hitherto scholarly work on green facades addressed the functionalities in milder climates. Vox et al (2018) studied green facades (of evergreen plants Pandorea jasminoides variegated and Rhyncospermum jasminoides) to control (perforated brick) wall surface temperature, based on two years of experimental data in a Mediterranean climate. Taylor et al (2016) found that shrubs and climbers on the mock-up walls improved the performance by 20-30% during the winter in Sheffield. Bolton et al (2014) claimed 8% energy savings with English ivy (Hedera helix) covering a solid brick-walled building in Manchester, UK Most of the hitherto scholarly work on green facades addressed the functionalities in milder climates. Vox et al (2018) studied green facades (of evergreen plants Pandorea jasminoides variegated and Rhyncospermum jasminoides) to control (perforated brick) wall surface temperature, based on two years of experimental data in a Mediterranean climate. Taylor et al (2016) found that shrubs and climbers on the mock-up walls improved the performance by 20-30% during the winter in Sheffield. Bolton et al (2014) claimed 8% energy savings with English ivy (Hedera helix) covering a solid brick-walled building in Manchester, UK

Objectives

Methods

Results

Discussion

Conclusion