Passively Recovering Waste Heat Energy With Every Shower

How many Recoup Pipe HEX WWHRS does it take to mitigate a Space Rocket launch?

Aug 4, 2021 | Energy Initiatives, Energy Saving

WWHRS vs Rocket Launch vs a Tesla

We saw a really interesting post from Tom Wood on LinkedIn regarding the recent SpaceX Rocket launch, asked how many Teslas Elon Musk would need to sell to ‘offset’ a space rocket launch? This got us wondering:

How many WWHRS pipes would a housebuilder need to install to ‘offset’ a rocket launch?

According to Tom’s research, each rocket launch can emit up to 2,683 tonnes CO2e, equivalent to about 5,000 people taking a return flight from London to the Costa del Sol. He then calculated that each Tesla could save up to 132 tonnes CO2 over its’ serviceable lifetime vs a typical petrol or diesel car over a similar lifespan. That means that each rocket launch could be offset in terms of CO2 emissions by the sale of 25 new Teslas vs 25 ‘average luxury’ cars, over a 250k mile lifespan.

Rocket to New Teslas

So what about Waste Water Heat Recovery Pipes compared to a rocket launch?

Can WWHRS really save enough energy to make any difference? The results might surprise you…

Based on a 3 bedroom, 2 bathroom home, with 4 occupants and a single Recoup Pipe HEX attached to showers in an ensuite and family bathroom (and current SAP defaults for showering and shower frequency), we can calculate that each home can save between 0.32 and 0.53 tonnes of CO2 per year, vs the same home without WWHRS.

WWHRS reduces primary energy demand by recycling the waste heat energy that normally goes down the drain with each shower use and sends this energy back to the hot water system & shower mixer. In a new build home such as this, it can reduce the hot water required for each shower use by around 55%.

When we then calculate the total CO2 savings generated by WWHRS over a 40 year serviceable lifetime (the lower end of the MHCLG estimate), we then see that each home could save between 13.04 – 21.44 tonnes of CO2 depending on whether the DHW is heated by gas or electricity. When we average this out across the current relative percentage of fuel used in UK homes, we see that it actually only takes less than 199 Recoup Pipe HEX to be installed to offset the emissions from a space rocket launch!

Even we found this statistic pretty stunning (so much so, that we’ve dropped the spreadsheet in below, so it can be scrutinised): Less than 200 WWHRS units can save the equivalent CO2 to a trip into Space: “That’s out of this world!” But, equally, it also means that across their lifetime, around 8 Recoup Pipe HEX pipes can save the equivalent Carbon offset to that of a Tesla vs a standard fossil fuel driven car! …and each WWHRS can be installed in a new build at a similar cost to a domestic EV charger (but without the additional cost of the car to go with it).

WWHRS vs Rocket vs Tesla Carbon Calculations

If you wish to discuss WWHRS and how it could be used to help you achieve energy savings and contribute to your Part-L compliance specification, then please contact us.

The regulation states that any fluid of category 4 or 5 must be separated by a double wall in order to comply. It is generally accepted (but debateable) that the change of fluid category associated with showering is at the point of the trap for the shower where it passes from its lowest possible category of 3 to a category 5 fluid on joining the rest of the waste system. There are certainly some circumstances where the shower waste itself prior to the trap may be deemed as a category 5 fluid.

Therefore, in order for a single walled product to comply, additional design and installation requirements are required.

The primary implication of this it that a drainage trap must be installed downstream of the unit, and therefore a trap should not be installed before the WWHRS. Removing the trap from the normal position at the bath or shower tray, and then relocating it downstream of the WWHRS unit (often on the floor below the shower or bathroom), can present several significant issues to both the installer and homeowner:

Recoup WWHRS Learning

Recoup WWHRS Learning is our online education portal for all things waste water heat recovery. Made up of courses containing lessons and quizzes it goes from an introduction to waste water heat recovery for showers to product installation courses. Find out more here.

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