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SAP 2012 Changes - Waste Water Heat Recovery Systems

SAP2012 was unveiled under a cloak of darkness and without fanfare at the start of June. Until Part L is confirmed and released in England and Wales (and the updated Section 6 in Scotland), the SAP methodology will not be used, so we’ve got a few months to understand what’s changed, and how that may impact next year’s building projects.

Over this series of blogs, we’ll look at SAP2012 in detail:

There are now several companies selling waste water heat recovery systems… and they’re clearly becoming more popular, as the new SAP covers the devices in more details than ever before.

At a basic level, we’re talking about a clever piece of plumbing. The waste water from baths and showers goes down the plug-hole in the usual way, but some of the heat is captured as waste energy.

This energy is then transferred to the cold water which is heading to the shower, and pre-heats it. This means less energy is required to bring it up to temperature.

What is a Waste Water Recovery system?

Waste Water Heat Recovery is essentially a pipe within a pipe. Cold water flows in the outer pipe, and the hot, unwanted water flows through the inner pipe.

Or, to put it another way, one of the companies producing this system is Showersave – they  say their product ‘is installed as part of the waste system and as hot water passes through the inner bore of the heat exchanger, cold mains water is delivered simultaneously through the outer part of the heat exchanger, heating up as it goes.’

Now, waste water recovery technology isn’t new to SAP, but until now the energy savings have only applied to instantaneous systems (so each unit applies to one/two showers max, and when you switch the shower off, there’s no hot water flowing through the system, so you don’t see any savings.

What's new?

For the first time, SAP2012 will take into account savings from waste water recovery systems which include a water store.

Energy is collected in the same way, but is then pumped through to the hot water system of the dwelling, pre-heating the tank. This means all wet rooms and kitchen can benefit from the savings.

This system requires some energy to power the pump, but in return should offer higher savings on your hot water bills. The cost of the storage system is typically more than an instantaneous system.

Currently, only one range of products (from the company Re-Aqua) has been certified (as of June 2013).

Next in the series of blogs we will look at the SAP 2012 changes to Solar PV...For regular updates follow us on Twitter @EnergistUK

Jon Ponting

Author: Jon Ponting

This article was published by Jon Ponting on 26.06.2013.