Modern Housing Retrofit: Assessment of Upgrade Packages to EnerPHit Standard for 1940–1960 State Houses in Auckland

Paola Leardini,Manfredo Manfredini

doi:10.3390/buildings5010229

Abstract

New Zealand state housing includes a significant portion of problematic buildings constructed after the public housing scheme launched in 1936. Most of these houses are still uninsulated, thus, cold, draughty, mouldy, and progressively decaying; however, as they are fundamental elements of the country’s culture, society, and environment, and are built with good quality materials and sound construction, they are suitable candidates for effective energy upgrades. This paper presents findings of a study on problems and opportunities of retrofitting the state houses built between 1940 and 1960 in the Auckland region. It advocates strategic national policies and initiatives for retrofitting, based on more challenging performance thresholds. The research defines and virtually implements an incremental intervention strategy including different retrofit packages for a typical 1950s stand-alone house. Indoor and outdoor environmental parameters were monitored over a year, and data used to establish a base case for thermal simulation. The upgrade packages were then modelled to assess their impact on the house’s thermal performance, comparing heating requirements and comfort of various insulation and ventilation options. The paper reports on effective ways of preserving the integrity of such a house, while improving its thermal performance to the EnerPHit standard, and discusses the benefits of introducing this holistic approach into New Zealand retrofit practice.

Highlights

According to the International Energy Agency, buildings are responsible for 32% of the total final energy consumption and around 40% of the primary energy consumption in most of its member countries [1]
Overall results of Passive House Planning Package (PHPP) calculation confirm the impact on energy savings of different insulation and airtightness improvements that was found with VE thermal modelling—assuming constant indoor thermal comfort conditions associated with air temperature equal to 20 °C
The research discussed in this paper challenges the current New Zealand retrofit practice that, driven mainly by financial return, disregards social, cultural and environmental matters lying beyond regulatory prescriptions and engenders severe problems of health, energy waste and building decay

Summary

Introduction

According to the International Energy Agency, buildings are responsible for 32% of the total final energy consumption and around 40% of the primary energy consumption in most of its member countries [1]. The growing awareness of the impact of the built environment on energy security that started with the 1973 oil crisis has made building energy efficiency a common target of many national energy conservation policies It has produced a wide variety of analytical, certification and rating tools aimed at assessing and enhancing the energy performance of new buildings. An increased effort towards consistent inclusion of the existing stock in policies and programmes for the improvement of energy efficiency is crucial to achieve tangible savings in building-related energy consumption and CO2 emission reduction This is relevant, as in many urban transformations retrofitting is often more effective than demolition and reconstruction in both economic and environmental terms as demonstrated by studies using Life Cycle

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