This section gives guidance on insulating pipework and ducting serving space heating, hot water and cooling systems in new and existing buildings to meet relevant energy efficiency requirements in the Building Regulations.
The insulation of pipework and ducting is essential to minimise heating system heat losses and cooling system heat gains. For cooling systems, it is also important to ensure that the risk of condensation is adequately controlled.
11.2 Scope of guidance
The guidance in this section covers insulation for the following types of pipework and ductwork serving space heating, domestic hot water and cooling systems:
• pipework: direct hot water, low, medium and high temperature heating, and cooled
• ductwork: heated, cooled and dual-purpose heated and cooled.
11.3 Insulation of pipes and ducts in new and existing buildings
Insulation of pipes and ducts serving heating and cooling systems should meet the following recommended minimum standards. The relevant standard for calculating insulation thickness is BS EN ISO 12241:200851.
a. Direct hot water and heating pipework
i. Pipework serving space heating and hot water systems should be insulated in all areas outside of the heated building envelope. In addition, pipes should be insulated in all voids within the building envelope and within spaces which will normally be heated, if there is a possibility that those spaces might be maintained at temperatures different to those maintained in other zones. The guiding principles are that control should be maximised and that heat loss from uninsulated pipes should only be permitted where the heat can be demonstrated as ‘always useful’.
ii. In order to demonstrate compliance, the heat losses shown in Table 39 for different pipe sizes and temperatures should not be exceeded.
b. Cooling pipework
i. Cooling pipework should be insulated along its whole length in order to provide the necessary means of limiting heat gain. Control should be maximised and heat gain to uninsulated pipes should only be permitted where the proportion of the cooling load relating to distribution pipework is proven to be less than 1% of total load.
ii. In order to demonstrate compliance, the heat gains in Table 40 for different pipe sizes and temperatures should not be exceeded.
iii. Although unrelated to meeting relevant energy efficiency requirements in the Building Regulations, provision should also be made for control of condensation by following TIMSA guidance52.
c. Heating and cooling ductwork
i. Ducting should be insulated along its whole length in order to provide the necessary means of limiting heat gains or heat losses.
ii. The heat losses or gains per unit area should not exceed the values in Table 41. Where ducting may be used for both heating and cooling, the limits for chilled ducting should be adopted since these are more onerous. (Heat gains are shown as negative values.)
iii. As with pipework, additional insulation may be required to provide adequate condensation control, as detailed in TIMSA guidance.
****Table 39 Recommended maximum heat losses for direct hot water and heating pipes****
****Table 40 Recommended maximum heat gains for cooled water supply pipes****
****Table 41 Recommended maximum heat losses and gains for insulated heating, cooling and dual- purpose ducts****