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The purpose of this paper is to report on a study which has been carried out on a timber floor construction above a ground‐supported concrete slab, which was used in small detached houses built in Sweden during the period 1960‐1990. This method of building has turned out to be a risky construction nowadays, but there are 800,000 houses built this way in Sweden.

By using the patented Air Gap Method inside building constructions, harmful water can be dried out. The method ventilates air gaps inside walls and floors with an air flow driven by thermal buoyancy caused by a heating cable in the vertical air gaps. The drying out process has been studied both by measuring the moisture level in the slab and also by measuring the humidity transport and comparing this with air flow measurements.

The paper shows that the Air Gap Method manages to dry out water from both the slab and the overlaying wooden construction. The study shows also that the relative humidity (RH) levels in the air space below the floor are reduced in a significant way, thus minimizing mould growth. It is also shown that a thin layer of concrete upon floor beams prevents mould to grow even in a humid situation.

The research reported in this paper is only concerned with timber‐framed small detached houses. Similar studies of apartment buildings are ongoing.

The Air Gap Method can thus be useful in the context of renovating a water damaged house of this type built during this 30‐year period. The method provides a possibility of drying out such damage without a separate drying period. The inhabitants could therefore be able to use a renovated water‐damaged kitchen six/eight weeks earlier compared to ordinary building methods.

The paper is useful because it provides better understanding of the mechanism of RH inside a building construction and how this parameter could be lowered. The paper is also useful in the context of renovating water‐damaged small detached houses built by the risky method of construction used in the last decades of the twentieth century.

Water damage is a severe problem in modern construction, causing economic loss and health implications. By using the patented Air Gap Method inside building constructions, harmful water in the construction can be dried out. The method drains and ventilates air gaps inside walls and floors with an airflow driven by thermal buoyancy caused by a heating cable in vertical air gaps. This paper aims to investigate this method and measurements of airflow inside air gaps of walls.

This study investigates the measured correlation between the power of the heating cable, the difference of temperature inside and outside the air gap, and the airflow. Data are collected by experimentation with a full‐scale constructed wall.

The study finds that airflow increases with raised temperature difference between the air gap and room and with raised power of the heating cable. The measured airflow reaches values up to 140 m³/metre wall and day for one cable. A small increase in temperature, between 0.2 and 0.3 ^oC inside the vertical air gap results in an air flow of approximately 60 m³/metre wall and day. The air change rate per hour for the air inside the wall construction varies between 15 times for a 6 W/m cable and 37 times for a 16 W/m cable.

The method provides the means to build houses in a more robust way, minimising the negative effects of water damage. This investigation provides an understanding of how temperature and ventilation are related in this method of construction.

The issue of ventilated construction is rarely investigated in scientific research.

The purpose of this paper is to promote energy saving measures concurrent with major planned renovation/refurbishment in residential buildings.

The methodology comprises of case studies, in which the influence of various factors is identified on the overall decision making related to building renovation/refurbishment.

The employed operational decision support process enables energy saving opportunities for residential buildings in conjunction with planned major renovations/refurbishments.

The research scope is confined to residential buildings in Sweden and cooperatives with tenants as the owners and governors.

A novel approach to synergistic energy saving and renovation in residential buildings is exhibited.

The paper presents an altered viewpoint of energy renovation means for residential buildings in the built environment.

The paper presents a novel approach for building owners to renovate a building in terms of improved performance, energy efficiency and indoor comfort in combination with planned renovations/refurbishments.

Water damage is a severe problem in modern construction, causing economic loss and health implications. The patented Air Gap Method, which is a slight modification of the common infill wall construction, provides means to build houses in a more robust way, minimizing the negative effects of water damage. This full‐scale study of the method aims to show how walls and floors may be built to create ventilation within the construction, with air gaps equipped with heating cables. The general hypothesis is that the patented Air Gap Method drains and evaporates dampness after water damage. The purpose of this study is to show how the method is built and how the method deals with water damage, such as a flooding, and with mould growth.

The Air Gap Method is based on a common timber‐framed construction and is completed by the provision of inlets, air gaps, slits, and outlets. The power for the convective airflow is given by an electrical heating cable. The study was carried out as a full‐scale experiment using a 24 m² large apartment build by this method. This apartment was flooded with 120 litres of domestic wastewater and the drying period was compared when heating cables were switched on or not. Mould growth was also investigated.

The method dries out a flooded floor in nine days when two heating cables were switched on, in 13 days with one heating cable and 21 days when the heating cables were off. The method prevents all mould growth provided that the indoor RH is lower than 65 per cent.

The method provides means to build houses in a more robust way, minimizing the negative effects of water damage.

The issue of ventilated construction is rarely investigated in scientific research.