households to improve the energy efficiency of their properties and reduce heating bills. A large number of properties that had the insulation installed by successive UK government-backed schemes were installed incorrectly or were unsuitable for the property. Incorrectly installed cavity wall insulation (CWI) causes water to seep into a property's walls, causing structural problems and damp patches that may also manifest into mould. In some cases, the damp and mould resulting from CWI can cause health problems or exacerbate existing conditions, particularly respiratory conditions. This has led to the formation of the Cavity Wall Insulation Victims Alliance (CWIVA). On 3 February 2015 the CWIVA took the debate to the houses of parliament discussing the cavity wall insulation industry. Issues Breathing performance; early cavity wall buildings exchange moisture readily with the indoor and outdoor environment. Materials used for repairs must be selected with care to not affect the materials' breathing performance. Cavity wall insulation installed in older buildings can create problems with moisture retention. Thermal mass cavity walls are thick walls. These help stabilize the interior environment of a building better than thinner modern walls. Environmental Influences: The orientation or design of a building may affect the performance of different façades on a building. Some walls may receive more rainwater and wind than others depending in their orientation or protection to some of the faces. Moisture is one of the main problems in materials weathering. References External links Whittemore, H. L. (1939). Structural properties of a concrete-block cavity-wall construction sponsored by the National Concrete Masonry Association. Washington, D.C.: U.S. Dept. of Commerce, National Bureau of Standards . Whittemore, H. L. (1939). Structural properties of a reinforced-brick wall construction and a brick-tile cavity-wall construction sponsored by the Structural Clay Products Institute. Washington, D.C.: U.S. Dept. of Commerce, National Bureau of Standards . Brick Cavity Walls: A Performance Analysis Based on Measurements and Simulations. Journal of Building Physics. October 2007 v31: p95-124 Article must be purchased. Cavity wall, Energy Saving Trust Cavity wall insulation (CWI): consumer guide to issues arising from installations, 14 October 2019, Department for Business, Energy & Industrial Strategy Cavity Wall Insulation Victims Alliance Masonry Construction Types of wall