Energy Saving With Stormdry
Keeping Walls Dry
When masonry gets wet it loses its insulation properties, much in the same way that wet clothes make you feel cold. By creating a deep water-repellent zone on the masonry surface, Stormdry ensures that the masonry remains dry throughout the year – maximising its thermal resistance or “R” value. This reduces heat loss through the masonry, thereby saving energy.
Reducing Carbon Emissions from “Hard to Treat” Properties
The UK Government has set a target of an 80% reduction in carbon emissions by 2050. Much of this will have to be met by reducing the carbon footprint of the UK’s housing stock.
It is estimated that 85% of UK’s existing housing stock will still be in use in the year 2050 so, even if we build a new generation of “green” homes, measures will still have to be taken to reduce the carbon footprint of the existing housing stock.
In most cases, the easiest improvement can be achieved by upgrading loft insulation to reduce heat loss. However, this measure will not address the large proportion of heat loss that occurs through the walls of a building. Where a house is built of cavity wall construction, cavity wall insulation can provide an effective solution. However many houses are built of solid wall construction or have cavity walls that are not suitable for cavity wall insulation (e.g. cavity too narrow). These properties often fall under the “Hard to Treat” or “HTT” category used by housing professionals to denote properties for which reducing energy consumption presents difficulties for technical, economic, or social reasons.
Traditional Insulation Options for Solid Wall Properties
Internal insulation takes up floor space traditionally there have been two wall insulation options for properties constructed from solid walls (or from cavity walls that are not suitable for cavity wall insulation). These are internal insulation and external insulation. Both of these types of insulation can be very effective, however, they are not suitable for all properties.
In many cases internal insulation is not suitable because it would cause an unacceptable reduction in room size or is not practical to install without significant disruption to the occupants. External insulation has the effect of altering the appearance of a building which is not always desirable – particularly in the case of buildings faced with brick or stone.
Stormdry Offers a Solution
In most cases the energy savings achieved by treating masonry with Stormdry will not be as high as those achieved using internal or external insulation. However the use of Stormdry has the advantage of allowing the thermal resistance of walls to be improved on “hard to treat” properties that would not otherwise be insulated. For this reason Stormdry has an important role to play in reducing carbon emissions from buildings. Because Stormdry is applied to the outside of the building, disruption to the occupants is minimised.
In order to prove the concept of improving the thermal resistance of walls using Stormdry a preliminary test was carried out at the University of Portsmouth comparing the thermal resistance (R-value) of a wet brick with that of a Stormdry-treated brick. This test demonstrated that the thermal resistance of the Stormdry-treated brick was more than twice that of the wet brick. In order to estimate the thermal benefits of treating walls with Stormdry in the real world further testing and modelling was carried out:
Model House Experiment
Further testing carried out by the University of Portsmouth involved the comparative testing of a treated and untreated model house placed in an environmental chamber. During the experiment, the energy required to maintain a stable 20ºC temperature within the model test house was measured. Energy savings of between 5 and 9% were demonstrated in a single brick width wall from the result of changing outside temperature and humidity alone, indicating that energy savings are possible even during periods of no rainfall. A 50% energy saving was demonstrated during a single wet “rain” event.
SAP Analysis and Supporting Data
In order to try and estimate the energy savings possible in the real world data was obtained from BRE and Fraunhofer publications giving examples of moisture contents of exposed masonry walls. This data together with the data obtained from the University of Portsmouth experiments (above) was used to carry out SAP1 analysis on a semi-detatched solid wall house. Depending on the weather locations used, energy savings of between 7 and 27% were predicted by the model. The SAP model does not take into account evaporative cooling effects which make a small further contribution to potential energy savings.
Scaled up testing is now being carried out in conjunction with the University of Portsmouth.