As further steps are being taken to meet government targets to reduce CO2 emissions,building services are coming under pressure to be more energy efficient.This has led to some debate about whether certain products require insulation,and confusion as to what is required to comply with BS 5422: 2001,requirements that are likely to become if anything tighter and more firmly embedded in the law following the current review of Part L.
These products include plastic pipes,which are increasingly being specified and used in the HVAC industry.Some manufacturers claim that by using plastic pipes either the thickness of insulation can be reduced or that no insulation is necessary at all,because plastic is a better insulator than the more traditional metal pipe work.This is an oversimplification and is misleading,as is the implication that significant savings can be made by reducing the level of insulation.
It is certainly true that the thermal conductivity of plastic pipes (0.16 – 0.22 W/m.K)is low compared to copper(385 W/m.K)or steel (63 W/m.K),but it is still high when compared with insulation (0.021 – 0.040 W/m.K).For example,a plastic pipe wall thickness of 10 mm is equivalent to approximately 1 to 2 mm of phenolic insulation.Bearing in mind that pipe insulation is manufactured in 5 mm wall thickness increments,this is simply not significant enough to allow the insulation thickness to be reduced,and certainly not enough to lose the insulation altogether.
The graph demonstrates the thickness of rigid phenolic insulation that would be required to comply with BS 5422:2001 for varying pipe sizes in both plastic and steel and takes the example of insulation for non-domestic hot water (60oC)to control heat loss.Substituting other insulation materials for phenolic insulation would yield a similar graph.
These figures are based on an estimated mean temperature of +50ºC,an assumed thermal conductivity of 0.025 W/m.K for the insulation,0.22 W/m.K for the plastic pipe,and 50 W/m.K for the steel pipe.In spite of the better thermal performance of the plastic pipe,there is clearly no case for reducing the amount of insulation needed.
Most importantly,BS 5422:2001 does not make any allowance for the use of plastic pipes;failure to install the specified insulation thickness would not meet the standard’s requirements and may therefore be in contravention of Part L of the Building Regulations.
Moreover,the proposed revisions to Part L indicate that the requirements are likely to get tighter rather than be relaxed.
The current proposed amendments to Part L require that “Reasonable provision shall be made to limit heat gains and losses through the fabric of the building and from pipes,ducts and vessels used for space heating, space cooling and hot water storage.”
BS5422:2001 is cited as the method for specifying thermal insulating materials for pipes,tanks,vessels,ductwork and equipment operating within the temperature range -40°C to +700°C.
Contractors may like to consider that BS5422:2001 has been written into Approved Documents L1 and L2 of the Building Regulations in order to ensure that the level of insulation on Building Services is in line with the Government’s commitment to reduce CO2 emissions.Any lessening of the levels of insulation laid down in the standard is therefore contrary to the Energy Policy of Europe and the UK,and would be in contravention of the law.
Quite apart from the legal requirements,there are of course long term benefits to be had from the efficient insulation of pipes in the shape of reduced energy consumption.This type of whole life cost analysis for products and structures is becoming an increasingly important part of specification.It is short sighted indeed to try to reduce costs now by skimping on long term cost effective elements such as insulation. In the long run this would prove costly for both the end user and the environment,and if the building doesn’t comply, costly too for the contractor,since it is far easier to put insulation in place at the outset than it is to have to apply it remedially.
In summary,the insulating properties of plastic pipes are so insignificant that they have a minimal effect on the thickness of insulation needed to meet the requirements of BS5422:2001,and therefore Part L.Claims that plastic pipes need not be insulated or that they require less insulation should be treated with caution.
Luckily there are pipe insulation products available on the market that are thermally effective, easy to handle and install and cost effective.Why risk non-compliance when there are such simple solutions to hand?
- Shedding light on office lighting design
- Air source heat pumps - how do they compare to...
- A Glossary of construction terms
- Redundancy - a checklist
- How underfloor heating drives down whole-life...
- Time obligations in building contracts and rem...
- Avoiding corrosion
- Why chilled beams have hit the roof
- WHOLE-HOUSE VENTILATION SYSTEM RESPONDS TO MOD...
- How limited are your downlighter covers?
There is an obvious need for the industry to be more energy efficient and pay more attention to the ways in which energy is both used and wasted. Do you think we have the products on the market to meet our needs?
