Reviews the present state of development of dynamic insulation systems. Describes the advantages and disadvantages and assesses probable applications. Earlier articles and reports on dynamic insulation are listed and commented on. The second part deals with the ventilation design aspects for practical application of dynamic insulation in buildings. One of the points is concerned with how the air flow through the insulation is affected by changing external climate conditions. The risks of condensation in the insulation, particularly with coincident flow systems, is discussed.
Ventilation requirements for the reduction of humidity. Required air change rates for hygiene and moisture removal for various rooms are given. Air flow rates are calculated for natural ventilation with closed windows, hopper windows and controlled ventilation. Ventilation by window opening is discussed. Gives examples of the transfer of moisture within a building, and the main reasons for ventilation, with particular emphasis on moisture removal. Lists danger of condensation on various building elements, causes and remedies. Advises on ventilation measures.
It is necessary to design the ventilation system to avoid excess humidity in the apartments. Discusses the sources of moisture release in rooms, properties of air temperatures in relation to moisture absorption, condensation in bedrooms in particular, and moisture damage to building fabric. Advises on ventilation measures to control humidity.
A previous paper analysed a mathematical model of a non-condensing cavity. This paper extends the analysis of the first paper to analyse the seasonal moisture behaviour of a condensing building cavity. Climate statistics are used to calculate the duration of the winter wet-up period, and a rate of condensation formula is integrated to give total winter condensation. Although engineering design calculations cannot yet be attempted, some illustrative examples are given based on field data. The results give preliminary verification of the model analysed in both papers.
Evidence of the importance of air infiltration in moisture control in building structures has been steadily accumulating. A general model of moisture behaviour in structures has been built up including for the effects of cavity air leakage, for the hygroscopic behaviour of timber, for the effects of condensation and various geometric factors.
Examines the causes of condensation problems and ways of reducing or eliminating them. Deals with diffusion through the building envelope, mechanical dehumidification and ventilation. Considers condensation inside cavities and roof spaces.
States that the higher internal humidity and lower structural temperatures in UK timber frame houses, as compared to the US and central Europe increases the risk of interstitial condensation. Condensation risk has also increased in all countries because of energy conservation measures and changes in heating patterns, occupation density and moisture production. Gives recommendations for the prevention of interstitial condensation.
Describes trials undertaken by BRE and ECRC at Inverclyde to test small domestic electric dehumidifiers in council houses. Assesses 3 types of machine, selected to give a range of extraction rates from 1-4 kg per day. These were supplied free of charge and the running costs reimbursed. Shows that the equipment did lower the moisture levels in the houses satisfactorily. Preliminary analysis of results show that the early BRE model predicting moisture and ventilation interactions work well.
A small test house having a pitched roof/ventilated attic was installed in a high bay environmental chamber. The test house and its attic were extensively instrumented for measuring heat and moisture transfer. The test house was exposed to a ser
Discusses the possible effects of wind, stack effect, vents and fans on air leakage, and the influence of air leakage openings and the location on the pattern of air flow through buildings. Considers the possible extent and location of condensation in relation to these patterns, as well as methods of controlling moisture entry and removal of accumulated moisture.