Insulating properties

Article from Local Government News, November 2005

TopFloor's the way forward

In response to an ever increasing requirement for high-performance thermally efficient
buildings, and the desire to drive down energy bills, the problem of hard-to-heat homes is being tackled by improving insulation levels within their floors. George Pickard explains.

The insulation U-value of 0.25W/m2K for floors, as specified in the Building Regulations, is easily
achieved. At the same time, there is the flexibility of a 'trade off' between the various insulation elements within the building.

Roof, wall and floor insulation elements work in unison to provide the total solution to escaping heat. If one element performs below standard, it will act as a heat sink and the insulation of the whole building suffers, with consequential problems of condensation.

Among proposed new regulations being considered are improvements to insulation based on standalone elements, with the carbon index and CO2 emissions involved during the manufacture of insulating materials influencing the calculation. Estimates of anticipated U-values for floors are 0.22W/ m2K (January 2006) and, in the near future, down to 0.20W/ m2K.

So why do the regulations need to change? Amazingly, 42 percent of all the energy generated in
Europe is consumed in buildings, with space heating accounting for most of this.

We are all aware that the increasing production of CO2 is leading to global warming and climate
change, but there is also a current issue much closer to home. Poorly insulated, cold, damp homes
(which are inadequately heated) have repeatedly been linked to ill health and early death among the most vulnerable in society. If we were to insulate floors to the proposed U-value, it is estimated that the lower heating bills would recoup the cost of the insulation inside three years.

The Government has signed the Kyoto agreement which commits the UK to reducing carbon dioxide emissions by 12.5 percent from its 1990 levels by 2008-2012. Much of this saving will be achieved by increasing the energy efficiency of existing and new buildings. Insulation is widely accepted as one of the most effective ways of reducing energy consumption.

Flooring insulation products often incorporate polystyrene (EPS). Since its inception in the early 1970s, this has been free of CFCs and HCFCs, which were subsequently banned in 1994. As EPS also possesses a zero Ozone Depletion Potential and a zero Global Warming Potential, it is clearly an excellent insulating material with respect to CO2 emission and climate change.

Beam-and-block construction with an EPS over-layer has been used extensively over the past 25 years. As U-values have become more stringent, the depth of this polystyrene layer has increased from 40mm to as much as 100mm. Therefore, the overall floor construction has become deeper. The introduction of EPS panels as an alternative approach reduces the depth of floor construction to a minimum.

EPS infill panels are now fast replacing the traditional standard building blocks between T-beams as the ground floor construction of choice. This solution is robust and aims to achieve the BRE 120-year durability standard. Recognizing that the underside of the beam-and-block floor will be castellated, flooring manufacturers have introduced a flange onto the bottom of the panel to cloak the underside of the beam. Other areas such as perimeters where cold bridging may occur are dealt with by additional EPS edge strips.

Insulated floors can cater for membranes (airtight, methane radon), under-floor heating systems, and concrete topping power floated, such a topping save up to two weeks on the build programme – music to all construction managers' ears!

Other advantages include less manual handling, ease of cutting with a hand saw and reduced
environmental impact of delivery vehicles. In short, there is every reason for contractors to use insulated EPS floors.

Members of the Precast Flooring Federation can offer technical advice on thermal and structural
performance on their range of products.

The products themselves have been thoroughly tested, proven and meet the standards required by the NHBC, with the appropriate BBA certification, insulated floors are the floor specification of choice.