PDHU options ranking revealed - and it's as we feared!

The Council have provided an updated options ranking ahead of the 24th September working group meeting. We are very disappointed to see that the resident preferred option as identified in our survey (individual electric boilers) has been demoted right down to the bottom of the list. Please see below for our honest assessment of the top three options. We hope you're sitting comfortably!

The Council's top three options are:

1. “Do minimum”

2. River Source Heat Pumps

3. Mobile Heat Batteries

Notably, the SWAN option and the “do nothing” option have been removed from the ranking.

“Do Minimum”

The so-called “do minimum” option in the Council’s assessment is misleading. In reality, it involves full replacement and upgrading of all piping, while leaving the energy centre untouched. In fact, a true “do minimum” would be continuing the current maintenance programme and testing whether the system can be maintained, without immediately replacing everything. By ignoring this genuine baseline, the Council has structured the assessment to reach a predetermined conclusion.

From the start, the Council assumed the whole system must be replaced and called this “do minimum”. They compared only different replacement options, treating major capital investment as inevitable. This means the Council has asked not whether to replace the system, but only which replacement method to choose.

This approach breaches the government’s Green Book appraisal process, which requires any options appraisal to start from the existing situation as the baseline. A major change cannot be assumed from the beginning: it must be demonstrated by testing alternatives against “doing nothing”. By presenting “replace everything” as the “do minimum,” the Council has distorted the process and undermined any fair comparison of options.

Much later, the Council engaged FairHeat, not to test whether replacement was necessary, but to confirm the predetermined conclusion that full replacement is unavoidable. FairHeat’s role has validated a decision already made, leaving the consultation to focus on “how to replace” rather than “whether to replace at all.”

The new pipework the most expensive element of the project, costing up to £135 million.

Including this false “do minimum” option in the Council’s appraisal serves a strategic purpose: it makes the other PDHU upgrade options appear relatively inexpensive by comparison.

“Do Nothing”

“Do nothing” is the only true baseline against which all other options should properly be measured, but it’s been removed.

The Council has stated that the “do nothing” option was excluded from the evaluation on the grounds that it would not resolve existing or future heating issues at the PDHU. However, the stated purpose of the Future of PDHU project is to assess which options are most appropriate for the long-term provision of heat and hot water, which should include the potential decommissioning of PDHU and the use of independent heating systems such as in-flat boilers.

Throughout the process, the Council repeatedly assured residents that all heating options would be fairly assessed and that residents would have a meaningful role in shaping the outcome. In reality, residents have had little genuine influence over key decisions. In-flat electric boilers were only introduced as an option following sustained pressure from residents, having been dismissed outright by the Council at the outset. By now removing the “do nothing” option, the Council is effectively signalling that a full replacement of PDHU is the only outcome it regards as inevitable. 

River Source Heat Pump (RSHP) 

The RSHP option goes far beyond the so-called “do minimum” option. It involves full replacement of all piping, a new river-source heat pump, and a completely new energy centre. The energy centre would include a back-up energy supply from either a central gas or electric boiler, which represents a major upgrade over the current system.

For illustration, under this option, even if the river-source heat pump were to supply energy for 12 months of the year, both the heat pump and the boilers would still need to run together for 4 months to meet peak heating demand. This means the boilers must be maintained throughout the 8 months they are idle, at significant cost, to ensure they are ready to provide additional energy during the 4 months that they are required.

While water source heat pumps are a well-established technology, RSHP remain immature. RSHP face additional operational and regulatory challenges and no successful projects of this size currently exist in England. The RSHP option requires approvals from five separate regulatory authorities. A single rejection from any one of these five regulators could halt the project, even after millions of pounds have been spent on development.

By contrast, the independent electric boiler option is far simpler and lower risk, requiring approval from just one authority: building control. Despite this regulatory simplicity, the Council ranks direct electric very poorly, conveniently ignoring the practical and financial risks of more complex options like RSHP.

Mobile Heat Batteries (MHB)

The MHB option has evolved into the “hot water barge” option, which goes far beyond the so-called “do minimum” approach. Under this plan, hot water would be transported daily by barge from East London to Chelsea Bridge. It involves the complete replacement of all pipework, the construction of a docking terminal near Chelsea Bridge, the laying of an additional pipeline from the dock to the PDHU energy centre, and an upgrade to the energy centre itself.

This approach is untested in the context of urban district heating and raises serious concerns over cost and reliability. It is significantly more expensive than proven alternatives and introduces risks of failure, disruption and higher costs for residents. When better, cheaper and more reliable solutions already exist, it is wholly inappropriate to pursue such an unproven scheme at residents’ expense.

SWAN

The Council’s treatment of the SWAN option highlights major flaws in its options assessment process. The Council repeatedly stated that SWAN failed to engage and provide information, which is why the option was ultimately ruled out. Yet despite this complete lack of evidence or input, the Council still ranked SWAN as the number one option, until they removed it this month. That ranking was not based on facts or data but on the Council’s own informal commercial assumptions. In other words, the Council promoted an option it knew was unsupported, only to later dismiss it on the grounds that it was unsupported.

If a leading option could be advanced on nothing more than guesswork, residents are entitled to ask how robust or trustworthy the evaluation of any option really is. At best, it shows inconsistency; at worst, it risks misleading residents about what heating options are genuinely viable.