Across the UK, social housing providers are making progress toward net-zero targets through the “fabric-first” approach which focuses on improving the building envelope. This includes insulation, sealing draughts, replacing windows, and improving ventilation, all designed to reduce heat loss and lower space heating demand. These upgrades are vital and form the foundation of any effective retrofit programme.
However, once the fabric is improved and space heating loads fall, the balance of household energy use begins to shift to the next largest source of energy consumption, namely hot water supply.
Why Hot Water Matters
In many upgraded homes, domestic hot water represents 25% to 40% of total building energy consumption. EPC certificates should give projected kWh required for hot water within homes, and figures of 2,000 – 2,500 kWh / year are not at all uncommon. Showers are by far the biggest part of that demand, regularly accounting for 80% or more of all hot water used within the home.
As such, once a home’s walls, roof, and windows have been insulated, showering as an activity becomes the most significant source of energy consumption. Addressing it is key to moving beyond the first phase of retrofit and delivering the next step in decarbonisation.
Passive Solution, Significant Savings
This is where Zypho Waste Water Heat Recovery (WWHR) technology comes in. Zypho WWHR units are designed to capture the heat from shower waste water and use it to preheat the incoming cold mains feed before it reaches the shower mixer or hot water system. By recovering this otherwise lost energy, Zypho WWHR units reduces the amount of work that boilers or heat pumps must do to provide hot water, saving considerable energy every day.
The process happens instantly and passively, without any pumps or power. Once fitted, the unit simply works every time the shower is used, significantly lowering energy demand without any input from the user.
Zypho WWHR delivers meaningful savings at a low capital cost
In a social housing context, this makes Zypho shower heat recovery especially relevant. It provides a practical way to continue improving efficiency without major structural work or inconvenience to residents. Furthermore, residents get to enjoy considerable savings on their energy bills.
Zypho’s WWHR range includes both horizontal and vertical models suitable for various property types. The horizontal units, such as the iZi30 and Slim50, are compact and designed to fit beneath baths or shower trays. Specifically designed for easy installation, these units are ideal for retrofit projects where space is tight and access is limited. The typical installation time for a Zypho horizontal with a shower above a bath is about four hours for a plumber. Once installed, the system simply becomes part of the plumbing, operating passively in perpetuity.
Zypho WWHR systems are recognised in the SAP Product Characteristics Database and compliant with Part L 2021. As such they can be included directly in energy assessments for EPC and building regulation compliance. This means they not only save energy in practice but also contribute excellent value for money SAP points. All are compatible with funding streams such as the Social Housing Decarbonisation Fund (SHDF) and ECO4.
Vertical solutions
Horizontal solutions
Horizontal solutions
A Simple Retrofit to Tackle Fuel Poverty
Beyond retrofitting into existing bathrooms, it makes eminent sense to ingerate Zypho WWHR into any projects that are upgrading bathrooms, replacing hot water systems, or improving water efficiency. For social landlords, this integration offers a straightforward path to additional savings. Reducing hot water demand by such an extent can often result in lower thermal store tank sizes, which not only saves hundreds of pounds but also frees up much-needed space within homes. without increasing maintenance obligations.
Finally, in many social homes, Fuel Poverty remains a concern even after fabric and heating improvements. Hot water costs can represent a large share of household energy bills, with it not uncommon for a family to spend £500 / year on showering alone. Because Zypho WWHR can halve the energy required to heat water, the energy gains are considerable.
The Logical Next Step After ‘Fabric First’
As the retrofit programmes evolve, the sequence is clear: first reduce losses through better fabric and improve heating efficiency, then tackle hot water efficiency.
With showering accounting for the vast majority of hot water usage, Zypho WWHR is the perfect tool for the next stage in the retrofit journey.
