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ZYPHO Knowledge Centre
Learn more about how Zypho saves carbon and improves energy efficiency.
Why use Stainless Steel over Copper?
In the world of shower heat recovery, the use of copper as a material for construction is very commonplace. While this is driven by copper’s excellent thermal conductivity, there are a number of drawbacks to copper:
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Stainless steel is corrosion-proof
Shower waste contains not just water, but shampoo, conditioner and occasionally drain cleaners. Hair products are usually acidic (as low as pH 4) and contain a variety of salts; drain cleaners are usually strongly alkali. Acids, alkalis and salinity ALL actively attack copper, corroding it to the point of loss of integrity. Pinhole corrosion is usually the first sign of weakness, where mains pressure water sprays straight from mains into the drain – needlessly and continuously wasting huge amounts of water.
In contrast, the marine grade 316L Stainless Steel that our products are made from, will, by definition, never corrode in use. Instead it will remain shiny, effective and 100% robust for decades to come.
Whilst currently $8,500/tonne, copper has ranged from $4,500 in 2020 to $10,500 in 2021 and 2022. Such volatility makes long-term pricing hard. By comparison, stainless steel is a much more stable material for construction.
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Copper is attractive to ‘light fingers’ on site.
With even a single length of copper plumbing pipe selling for over £20, it is not surprising that copper can go ‘missing’ on site. The copper content alone of a shower heat recovery unit could be close to £100, and, as such, is very tempting to the unscrupulous. Stainless Steel does not have the same sort of attraction. For all these reasons, Zypho® has innovated the patented stainless steel vertical heat recovery unit. By clever design, we have increased the heat transfer area, thereby compensating for the lower thermal conductivity of stainless steel.
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Very volatile market pricing
Whilst currently $8,500/tonne, copper has ranged from $4,500 in 2020 to $10,500 in 2021 and 2022. Such volatility makes long-term pricing hard. By comparison, stainless steel is a much more stable material for construction.
For all these reasons, Zypho® has innovated the patented stainless steel vertical heat recovery unit.
By clever design, we have increased the heat transfer area, thereby compensating for the lower thermal conductivity of stainless steel.
Solar PV Energy Usage
Solar panels aren’t cheap.
The Energy Savings Trust estimates that installation will set you back £7,860 for a three-bed semi-detached house with four occupants, according to figures released in March 2023. But the figures will vary depending on the size of your home and how much energy you want to produce.
The most popular solar panel system size is between 3.6 kWp and 4 kWp, according to a survey of more than 1,000 solar panel owners. This size of system generates around 3,750 kWh of electricity per year on average for owners. For comparison, a home using a ‘medium’ amount of electricity gets through 2,900 kWh per year on average according to energy regulator Ofgem. A ‘high’ user takes 4,300 kWh per year.
How much energy will actually be used?
Keep in mind that solar panels generate most of their electricity during the day, so you may not be around to use it (unless you fit a home storage battery too). In fact, a survey of solar panel owners found that:
- 12% use less than ¼ of their solar output
- 34% use between a ¼ and ½
- 22% use between ½ and ¾
- 13% use more than ¾
So, you will still need to buy electricity from the grid, especially on dark winter evenings.
| House Size | Annual Electricity Usage | Number of Solar Panels | Average Cost | Total Annual Savings |
|---|---|---|---|---|
| 1 Bedroom | 900 kWh | 3 | £2,358 | £183 |
| 2 Bedroom | 1,800 kWh | 6 | £4,716 | £365 |
| 3 Bedroom | 2,900 kWh | 10 | £7,860 | £608 |
Solar Battery
A solar battery is a device that allows you to store excess electricity—including the energy your solar panels generate— so you can use or sell it later on. With a solar battery, you will typically use an extra 30% of your solar energy, allowing you to save £175 more per year on average and cut your carbon footprint by another 15%—which adds up to an extra tonne of CO2 per year.
The average cost of a solar battery for a three-bedroom house is £4,500. A smaller house will usually pay around £2,500 to add a solar battery to a solar panel installation, while a larger home will typically spend £5,500.
The larger the battery, the more electricity it can store, and the larger the benefit—but the higher the cost, naturally. Moreover, the price of adding a solar battery to a solar panel system means the average three-bedroom household will take an extra 12 years to break even on the whole installation.
| House Size | Annual Electricity Usage | Number of Solar Panels | Average Cost | Total Annual Savings |
|---|---|---|---|---|
| 1-2 Bedroom | 1,800 kWh | 6 | 4 kWh | £9,716 |
| 3 Bedroom | 2,900 kWh | 10 | 8 kWh | £16,860 |
| 4+ Bedroom | 4,300 kWh | 14 | 9.5 kWh | £22,005 |
Zypho® Savings
A key fact on PV in a Zypho context is comparing the energy that Zypho can save (%) with the amount of energy PV panels can generate in the UK (kWh). A 16-panel 4 kW PV system generates around 3,600 kWh/year, about 225 kWh/panel per year. If the typical household uses 2,000 kWh/year for hot water, we can work out the savings:
30%
600 kWh
2.7 PV panels worth
50%
1,000 kWh
4.4 PV panels worth
75%
1,50 kWh
6.7 PV panels worth
Zypho® Efficiency Gains
The degree of energy saved by the Zypho® systems depends on several variables including:
- Shower water flow rate
- Type of unit used
- Plumbing configuration
The lower the flow rates, the greater the degree of heat transfer, and thus the better the efficiency. Zypho has several different models for different applications, each with different heat transfer characteristics.
Flow Rate Percentages
| Model | iZi30 horizontal | Slim50 horizontal | PiPe60 vertical | PiPe65 vertical | PiPe75 vertical |
|---|---|---|---|---|---|
| Application | High flow horizontal for use in showers and showers above baths. | Most efficient horizontal on the market for showers and showers above baths. | Only viable where shower is on second floor or higher. | Only viable where shower is on second floor or higher. | Most efficient vertical on the market. Only viable where shower is on second floor or higher. |
| 5 l/m | 43.7% | 65.9% | 69.2% | 76.5% | 82.0% |
| 6 l/m | 40.1% | 61.2% | 67.4% | 72.8% | 79.3% |
| 7 l/m | 35.7% | 58.0% | 63.3% | 69.9% | 76.5% |
| 8 l/m | 33.1% | 54.9% | 60.1% | 64.4% | 71.6% |
| 9 l/m | 30.2% | 51.8% | 57.7% | 67.6% | 74.1% |
As per the SAP (PCDB) database. For reference, 6 litre/min is commonly regarded as a good shower flow rate, while electric showers typically deliver 3.5 litre/min.
What is SBEM?
SBEM (Simplified Building Energy Model) is a software tool developed by BRE that provides an analysis of a building’s energy consumption.
SBEM is used for non-domestic buildings in support of the National Calculation Methodology (NCM), the Energy Performance of Buildings Directive (EPBD) and the Green Deal. The tool is currently used to determine CO2 emission rates for new buildings in compliance with Part L of the Building Regulations in England and Wales, and equivalent Regulations in Scotland, Northern Ireland, the Republic of Ireland and Jersey.
It is also used to generate Energy Performance Certificates for non-domestic buildings on construction and at the point of sale or rent.
What does SBEM do?
SBEM is used to do two things:
- To demonstrate compliance with Part L of the Building Regulations and
- To produce Energy Performance Certificates (EPC).
An SBEM calculation provides an output in the form of a ‘BRUKL’ report.
What is a BRUKL Report?
A Building Regulation UK Part L Report (BRUKL) demonstrates compliance with certain aspects of new build regulations, including a carbon emission target (TER/Target Emission Rate), solar gain and limiting standards for fabric and services.
The BRUKL document is required by Building Control prior to works starting on-site. The BRUKL document is mainly required for new builds (and, in some cases, extensions), but can also be used for existing buildings, if any of the minimum standards are not met, to demonstrate the CO2 has been compensated for elsewhere.
Why is SBEM needed?
Any building that is not considered a dwelling (hotels, leisure facilities, commercial properties) will require an SBEM calculation to be produced as part of the design process. Compliance with Part L of the Building Regulations requires energy modelling of building designs in order to demonstrate low carbon performance.
SBEM compared to SAP
SBEM and SAP (Standard Assessment Procedure) are essentially the same in assessing the design of a property against defined standards. However, SAP more accurately reflects the carbon emissions of domestic properties and SBEM, of non-domestic properties.
WWRH and SBEM
Calculations can be made as part of an SBEM model to assess the impact of Waste Water Heat Recovery for Showers, reducing the CO2 produced by a building. The calculation focusses on the hot water (DHW) usage for showers within the building to indicate the CO2 reduction that could be made through WWRHS introduction.
A DSM1 is produced to provide statistics for Domestic Hot Water (DHW) based on one of the NCMs2 (National Calculation Methodologies). The calculation uses these figures along with the total hot water energy demand for showers, the energy recovered from the shower, and the efficiency of the WWHRS to calculate the CO2 reduction due to the waste water heat recovery system. The WWHRS recovery efficiency will then be applied to the total DHW heating demand as deemed by the SBEM calculation.
Including waste water heat recovery in the design of a hotel, leisure facility or other commercial building with showers can provide a significant CO2 reduction through SBEM modelling, particularly when compared to other more expensive measures such as PV, ASHP or triple glazing.
Zypho has a wealth of experience in assisting designers, architects and developers, incorporating WWHRS into both commercial and residential developments.
- Dynamic Simulation Modelling (DSM) is an extremely accurate and powerful tool for assessing the environmental performance of a building. Also known as thermal modelling, DSM can be used to model and analyse a range of sustainability factors typically arising from planning or building regulations drivers. These include energy compliance and CO2 emissions, overheating (thermal comfort) and daylighting analysis.
- The National Calculation Methodology (NCM) is a standardised framework developed to evaluate and calculate the energy performance of buildings. It offers a set of procedures, calculation methodologies and guidelines that enable accurate determination of energy consumption, carbon emissions and overall energy efficiency of a building. This calculation methodology is typically developed and implemented by governmental or regulatory bodies to ensure standardised energy assessments across the building sector. It provides a consistent and reliable method for assessing the energy efficiency of both new and existing buildings.
At Zypho®, we have always made the highest efforts to use materials most efficiently in all our products.
Copper
Whilst we need to use copper for heat transfer purposes on the current horizontal units, we are confident that it is used as efficiently as possible.
CO2
For the horizontal model (iZi30), the embodied carbon present (made chiefly from copper and ABS moulded plastic) equates to ~15.2 kg CO2e.
For the Slim50 model, the embodied carbon is 17.3 kg CO2e
For the vertical models, these are manufactured from Stainless Steel with some Polypropylene mouldings
PiPe65 = 59.8kg CO2e
PiPe75 = 65.8kg CO2e
“Payback”
As soon as the Zypho units go into operation in homes, all our products have rapid paybacks in terms of CO2.
| Model | Model iZi30 (Horizontal) | PiPe75 (Vertical) | Slim50 (Horizontal) | PiPe65 (Vertical) |
|---|---|---|---|---|
| Energy Saving Potential | ±500 kWh/year | ±1000 kWh/year | ±750 kWh/year | ±975 kWh/year |
| CO2 Saving Potential | 125 kg CO2/year | 250 kg CO2/year | 113 kg CO2/year | 244 kg CO2/year |
| “Payback Time” | 1.5 months
16.5 ÷ 125 = 0.13 years |
2.6 months
55.0 ÷ 250 = 0.22 years |
1.1 months
17.3 / 188 = 0.092 years |
2.9 months
59.8 / 244 = 0.25 years |
The carbon saving will depend on how the hot water is made, assuming:
- making HW costs 0.25 kg CO2 per kWh heat,
- the average household is using 1500 kWh HW per year on showering
Environmental Product Declaration (EPD)
Finally, it is important to note from an Environmental Product Declaration (EPD) point of view that, thanks to the passive operation of the Zypho unit, there is no running cost/operational carbon impact.
The standard EN1717, originally created for water tanks and not for WWHR (Waste Water Heat Recovery) specifically, is focused on preventing the contamination of freshwater by greywater (Level 5) as well as the backflow of greywater and gases.
Contamination can result from damage to the pipe wall, thus opening a channel for contact between grey and fresh water. With our vertical units, this is very unlikely to happen as they are made from stainless steel, not copper, which has far superior corrosion resistance, and the greywater circuit is not permanent or under any form of pressure.
However, as it is installed as a single-walled pipe, EN1717 calls for the use of a siphon/trap to prevent the rise of gases to the WWHR.
We believe that this should also be mandatory for a doublewalled pipe, and that EN1717 needs to be updated for the WWHR system.
We are already in contact with British Standard Institute (BSI) with the aim of having them validate the legitimacy of our point about the unsuitability of the EN1717 standard for the WWHR system.
More updates will be released as they become available.
What is BREEAM®?
BREEAM (Building Research Establishment Environmental Assessment Method) is the longest established method and most widely used third party certification scheme from BRE (Building Research Establishment) to assess the sustainability for planning projects, infrastructure and buildings. It recognises and reflects the value in using higher performing assets across the buildings life cycle, from new construction to in-use and refurbishment.
BREEAM was created by BRE to drive innovation and standards above the regulatory minimum, meaning that BREEAM-rated developments are more sustainable environments.
The Purpose of BREEAM
The aim of BREEAM is to reduce the impact of buildings on the environment through the early design and development stages, construction stage and the building’s life span. Not only does BREEAM determine a building’s level of sustainability but also the economic, environmental and social benefits that it has for the people linked to the life cycle of that building.
How does BREEAM work?
The assessment process comprises two stages:
- The Design Stage (Interim) and the
- Post-Construction Stage (Final).
Within these stages, there are assessment sections. The Energy Section aims to encourage the design and operation of energy efficiency buildings, driving energy efficiency, and sustainable energy use to ultimately reduce CO2 (carbon dioxide) emissions. BREEAM® awards points or ‘credits’, and groups the environmental impacts into to 10 categories, as follows:
- ENERGY: Operational energy and carbon dioxide (CO2)
- MANAGEMENT: Management policy, commissioning, site management and procurement
- HEALTH AND WELLBEING: Internal and external issues (e.g. noise, light, air, quality)
- TRANSPORT: Transport-related CO2 and location related factors
- WATER CONSUMPTION AND EFFICIENCY
- MATERIALS: Embodied impacts of building materials, including lifecycle impacts like embodied CO2
- WASTE: Construction resource efficiency and operational waste management and minimisation
- POLLUTION: Of external air and water
- LAND USE: Type of site and building footprint
- ECOLOGY: Ecological value, conservation and enhancement of the site
The total number of points or credits gained in each section is multiplied by an environmental weighting factor that takes into account the relative importance of each section. Section scores are then added together to produce a single overall score. Once the overall score for the building is known, this is translated into a rating on a scale:
| <10% | UNCLASSIFIED | – |
| >10% | ACCEPTABLE | * |
| >25% | PASS | ** |
| >40% | GOOD | *** |
| >50% | VERY GOOD | **** |
| >60% | EXCELLENT | ***** |
| >85% | OUTSTANDING | ****** |
BREEAM® and WWHR
For many developments, whether it be residential (houses, bungalows or apartments) or commercial (hotels, sports facilities or student accommodation), WWHR (Waste Water Heat Recovery) can contribute towards BREEAM® credits within the following sections:
1. ENERGY: Operational energy and carbon dioxide (CO2)
5. WATER CONSUMPTION AND EFFICIENCY
By using WWHR technology, the hot water production is drastically reduced, which saves energy, enhances efficiency and reduces the buildings CO2 emissions.
What is SAP?
The Standard Assessment Procedure (SAP) is the methodology used by the government to assess and compare the energy and environmental performance of dwellings. Developed by the Building Research Establishment in 1992, its purpose is to provide accurate and reliable dwelling energy performance assessments.
Part L of the building regulations uses SAP (since 1994) to assess a building’s energy performance. Reduced data SAP (rdSAP) was introduced in 2005 as a less costly method to assess the performance of existing dwellings.
How SAP Works
SAP assesses how much energy a dwelling will use while delivering a defined level of comfort and service provision. The assessment is based on standardised assumptions for occupancy and behaviour enabling a like-for-like comparison of dwelling performance.
Factors such as fuel costs and emissions of carbon dioxide (CO2) are determined from the assessment.
SAP quantifies a dwelling’s performance in terms of:
- Energy use per unit of floor area,
- A fuel-cost-based energy efficiency rating (the SAP Rating),
- The emissions of CO2 (the Environmental Impact Rating).
WWHRS and SAP
Waste Water Heat Recovery for Showers (WWHRS) is a listed technology on the Products Characteristics Database (PCDB). This database holds product information for a range of technologies used within different National Calculation Methodologies (NCMs) of which SAP and rdSAP are two. WWHRS specifically targets energy use in the home associated with hot water—and showering uses the largest proportion of that energy. Because of the amount of energy required to heat water, using WWHRS has one of the highest cost versus SAP impact ratios within the software. Savings are applied through the SAP modelling software to rooms with showers that have WWHRS connected to them.
The level of SAP impact is then determined by a few key factors:
- The number of occupants SAP has calculated for the dwelling
- The total number of rooms for showering/bathing
- The number of rooms with WWHRS attached
- If the room has only a shower or a bath and shower
- The system (A/B/C) installation method used
What is SAP10?
Coinciding with the new Approved Document Part L 2021, SAP1O is the new version of SAP. In SAP1O, the methodology has been updated to more accurately reflect the energy consumption of buildings.
One of the major changes to the calculations is the introduction of a new hot water model, which is more accurate than the previous versions of SAP.
In turn, this means that WWHR has a much larger impact (two to three times more effective) on the energy performance of a dwelling, making it even more cost effective than before.
Building Regulation Part L 2021 Edition
Effective from 15 June 2022, the 2021 edition of Building Regulation Part L will see the minimum requirement for a new dwellings energy performance increase significantly. In order for a dwelling to pass Part L, it will have to reduce its carbon emissions by approximately 30% compared to the previous standard.
The government has provided a ‘notional dwelling’ as an example of how to achieve this reduction and meet the new requirements. For a typical three-bedroom semi-detached house, it is done by including 1.5 kW of Solar PV and a WWHR system. Each of these measures reduce C02 emissions by approximately 15%.
What is interesting is how much more cost effective the WWHR is. With Building Regulations requirements changing and the SAP10 model giving more credit to WWHR, it is likely that WWHR will become a common technology in new-build homes.
Future Homes Standard
To be introduced in 2025, Future Homes Standard will require that all new homes be Net Zero Carbon constructions. This will reduce carbon emissions by a further 70%. It is anticipated that it will largely be met by utilising electricity generated from renewable sources as the primary heating source via heat pumps.
SAP Score Comparison
Installing Zypho WWHRS products is one of the most cost-effective ways to increase a building’s SAP score. The table shows the different products that can be applied to an SAP calculation, the typical SAP increase they provide and their cost.
You can see just how cost-effective Zypho is against other technologies:
ZYPHO® VS OTHER TECHNOLOGIES
| Product | Estimated SAP10 Increase | Product Cost | Installation Cost | Maintenance Necessary | User Interaction | Cost per SAP 1% |
|---|---|---|---|---|---|---|
| Zypho | 15% | £500 | £50 | N | N | £33 |
| Solar PV (1.5kW) | 15% | £4,000 | £500 | N | N | £300 |
| Insulation (increase by 50 mm to 150 mm) | 2% | £500 | £0 | N | N | £250 |
| Air Source Heat Pumb | 70% | £5,000 | £1,500 | Y | Y | £93 |
| Biomass Boiler | 65% | £10,000 | £2,000 | Y | Y | £184 |
| Solar Thermal | 15% | £3,500 | £500 | Y | N | £266 |
| MVHR | 3% | £1,000 | £500 | Y | N | £500 |
