R-values, humidity and health : case studies from Auckland Wellington

Abstract

The Auckland winter is rainy season. High indoor relative humidity is a major issue for Auckland housing indoor health conditions (Figure 1). According to international and national standards, the indoor relative humidity should be lower than 60% for indoor air quality [1-5]. Most of the health effects such as bacteria, viruses, fungi, mites, etc. have increases associate with very high indoor relative humidity (Figure 2). Maintaining indoor relative humidity between 40% and 60% can minimize the indirect health effects. The abundance of two major causes of allergy, mites and fungi in New Zealand housing, increase proportionately with average indoor relative humidity [6]. New Zealand has some of the highest levels of house dust mite allergens in the world [6]. Visible mould growth on indoor surfaces is a common problem in over 30% of New Zealand houses [