Waste Water Heat Recovery for Showers

WWHRS for Passive Houses

What is Passive House

Passive House (or Passivhaus) is one of the Worlds’ most rigorous design standards for both residential and commercial buildings. Enhanced air tightness and exceptional levels of fabric insulation underpin the Passive house design ethos, which can ultimately bring the space heating requirements in Passive house dwellings down to around 90% of that of typical building stock, and in many cases down to zero.

Hot water in a Passive House

A Passive House dwelling can save significant levels of energy through insulation and airtightness but the requirements for Domestic Hot Water (DHW) are roughly the same as they are in equivalent regular houses. Just because your house is super insulated, doesn’t mean you necessarily bathe more or take shorter showers. Therefore, the hot water generation in a Passive House (and many other super insulated homes) can form the largest part of the household energy budget, with the DHW energy requirement commonly being 3-4 times larger than the energy requirement for space heating.


Recoup WWHRS and Passive House

Passive House & WWHRS

In the average UK home showering accounts for 50% of the generated hot water cost. However, around 85-90% of this heat energy goes straight down the drain (42% of the total dwelling DHW budget).*

In a Passive House with a similar energy usage profile DHW generation accounts for 48.9% of the overall energy budget. Assuming the showering habits of those in Passive Houses do not differ from the average home, a staggering 20.8% of the energy used in passive houses could be pouring out of the building envelope via the shower drain.


Passive House energy saving and use pie chart

Waste water hear recovery (WWHRS) is designed specifically to capture this wasted heat energy and recycle it back into the building hot water system, and the good news is, it can be designed into Passive House as cheaply and efficiently as it can for any other newbuild dwelling. As an example the Recoup Pipe+ HE with efficiency of up to 67% could recover a significant proportion of this wasted heat energy.

WWHRS is a much simpler solution than some more common Passive House applications such as mechanical ventilation heat recovery (MVHR). There are no moving or mechanical parts; no planned maintenance; and no end-user interaction. It is a fit and forget passive technology that simply offers on-demand energy savings with every shower.

Recoup WWHRS products are listed on the Passivhaus Institute Certified Component Database, so can be used directly to contribute towards Passivhaus certification or PHPP (Passive House Planning Package) calculations. Additionally, the Recoup Easyfit+ is the ideal product solution for Passive House retrofits through ‘EnerPhit’ and ‘deep-green’ too. Contact us for any further information.

* Data gathered by the Energy Saving Trust from over 86,000 households


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