INSULATION
guidance offered within Approved Document B still allows a path for the use of combustible materials within the external facades of buildings over 18 metres, which are outside of those described in regulation 7(4), and have been subject to specific system testing and assessment. From 1 December 2022 Part B will extend the scope of this guidance to include buildings over 11 metres, specifically those with a ‘residential’ purpose (purpose groups 1 and 2) which will include hospitals, care homes, or other establishments in which people sleep. However, the use of non- combustible materials (those achieving a minimum class of A2-s1,d0) precludes the need for further testing. Stone wool is naturally non-
combustible which means it will not contribute to fire spread, nor will it emit significant toxic smoke if exposed to flames. There are stone wool insulation products that have been specifically developed for use within ventilated cladding systems, as well as sealed systems such as curtain walling. Some of these stone wool insulation solutions are manufactured using Dual Density technology. With these, the outer surface of each insulation slab features a distinctly higher density than the underside. This provides a firm and robust surface for the application of fixings, while the underside can accommodate unevenness in the substrate. Once installed, the higher density outer surface works in combination with a factory-applied water repelling agent to give improved resistance to rain ingress during construction.
Insulate to keep the temperature comfortable The main function of insulation in buildings is temperature control. It is vital to keep the indoor climate comfortable and healthy, which means effective temperature regulation as opposed to simply keeping heat in. With the recent climate changes, hotter summers mean that insulation is also needed to keep the heat out. The NHS has developed a Heatwave Plan3
increased demand to heat or cool buildings raises energy consumption, associated costs, and CO2
emissions.
Around 20 per cent of greenhouse gas emissions in the UK are caused by heating buildings.4
The EU has calculated that
proper insulation can reduce a building’s heating needs by up to 70 per cent.5 A measure of insulation effectiveness is
the U-value. It defines the rate of transfer of heat through a structure. A low U-value indicates low heat transmission. The U- value can be calculated for individual elements or the whole system.
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ROCKWOOL rainscreen insulation is non-combustible and reduces sound travel into buildings.
Thermal bridging – a gap in the system? Brackets used to fix cladding back to the substrate bypass the insulation, creating a path for heat loss which needs to be factored into the u-value calculation. This is known as thermal bridging. ROCKWOOL has a library of independently modelled scenarios which factor in the thermal loss which occurs through the brackets. This means that all components of the façade system have been accurately assessed with respect to the U-value. Every time the technical team is asked to calculate the U- value of a new system, they can apply the value for the bracket into the model and give the architect an accurate calculation, allowing for any potential thermal bridging caused by the bracket. Moreover, ROCKWOOL non-
that includes insulation as
one of the measures to combat the effect of hotter temperatures. Without appropriate insulation, the
combustible stone wool insulation can be easily fitted around brackets and other awkward details, and when tightly butted, adjacent slabs effectively ‘knit’ together to provide a continuous insulating layer, reducing heat losses that would otherwise be caused by gaps.
Benefits of insulation beyond temperature regulation While the driving force behind insulation specification is to regulate internal temperatures, the latest changes to Part B reflect the growing role of insulation
beyond thermal performance. Healthcare designers are increasingly recognising the wider performance benefits of insulation which can be designed into the building fabric - most notably acoustics.
Safe and sound What is considered noise is highly objective. In general, any unwanted sound can be a noise, no matter how loud. The fact that noise is harmful to hospital patients has been known for a long time. Even Florence Nightingale is quoted as having commented on it. Early attempts to reduce the noise levels featured the spreading of straw outside hospitals to dull the sound of horse hooves in the street.6
In addition to external noise from
traffic, construction work and other such sources, modern healthcare facilities generate internal noise from medical machinery as well as heating and ventilation systems that are needed to keep the building operational. Insulation has an important role to play in the reduction of these noise levels. It is easy enough to measure the noise within a space after it has been built, but by then, remediation can be very difficult and expensive if required. As such, it is important to accurately measure noise levels during the planning phase to ensure that the building design will deliver the
With the recent climate changes, hotter summers mean that insulation is also needed to keep the heat out
IFHE DIGEST 2023
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