Passivhaus, Herefordshire

Preliminary items

Upon the customer awarding the contract to WRE, prior to commencing the installation a number of detailed design items were undertaken. These were:

Heat Loss Calculations – to confirm the size of air source heat pump specified based upon the actual U-values of the various building elements, internally heated areas and internal design temperatures.

Wind & Snow Load Calculations – to confirm the roof was structurally capable of supporting the loads to be imposed upon it by the PV system.

Probable Water Demand Calculation – to establish the flow rate required from the incoming cold water main to meet the property water demands.

Distribution Network Operator (DNO) applications – to obtain connection offers to connect the proposed air source heat pump and PV system to the national grid.

Site survey

Prior to commencing installation work, a site survey was undertaken to go through the proposed works with the owner, Passivhaus builder and architect as set out in the formal design guide produced for the project following completion of the preliminary items design work.

The design guide, specific to the project, set out all the information associated  with the installation for reference by all parties involved, resulting in works progressing smoothly and an uncompromised end installation.

First fix pipework

The first stage of the installation was installing all of the first fix pipework throughout the building to transport the hot, cold and heating water from the plant room to its end locations. Pipework was sized to ensure the design flow rates at the sanitary ware outlets such as high flow showers, standing bath taps and wall mounted basin taps.

A press fit system was used to avoid bulky fittings so that all the pipework runs could be fully insulated to minimise heat loss.

First fix pressure test

Upon completion of the first fix pipework it was pressure tested to 1.5 times its working pressure to ensure it was free from leaks prior to the property being dry lined.

First fix pipework insulation

All first fix pipework was then insulated above and beyond building regulations to ensure minimal heat loss from, and transfer to adjacent pipework.

Armoflex insulation was used to insulate the pumped hot water return pipework to further reduce the heat loss from it due to the higher hot water temperature being circulated.

Waste pipework

Waste pipework from all the sanitary ware in the bathrooms, kitchen and utility was installed back to the soil stacks with the fall on the pipework was in strict accordance with building regulations to ensure waste water easily drains away without risk of blockage.

Waste water heat recovery

Waste water heat recovery units have been installed on each of the shower wastes to capture heat from the waste water and re-introduce it into the supply water to the showers.

First fix sanitary ware

Timber noggins were installed in the locations of second fix sanitary ware to ensure secure fixings were available following completion of the walls.

Ground floor underfloor heating castellation plates

Unlike a traditional ground floor construction where the insulation is laid under the concrete slab, because underfloor heating was being installed a reverse slab construction was adopted. The insulation was then laid on top of the concreate slab prior to the screed being laid over it containing the underfloor heating system. The insulation directly under the screed prevents heat from the underfloor heating system travelling downwards into the concrete slab.

To prevent the screed covering the underfloor heating system reacting with the insulation sheet, a polythene moisture migration barrier was also installed.

To allow for expansion of the screed containing the underfloor heating system, edge expansion foam was installed around the perimeter or all rooms containing underfloor heating.

 Rather than tacking or clipping the pipework directly to the insulation, castellation plates were installed. These ensured accurate and uniform pipe spacing as well as suspending the pipes to allow complete screed coverage around their full diameter. The plates also protected the pipes from foot traffic reducing the possibility of damage before the screed was laid.

Ground floor underfloor heating pipework completed

With the castellation plates in-situ, laying of the underfloor pipework circuits quickly progressed and once all the underfloor heating circuits were installed the accurate and uniform pipe spacing was evident.

Ground floor underfloor heating pipework tails and system fill and pressure test

Each of the underfloor heating circuits was returned back to the manifold location where they were meticulously cut to the required length and turned through 90° using pre-formed bends to ensure all pipes were uniform and unkinked before connecting them to their respective manifold.

Once all the circuits had been connected to the manifolds, the pipework was flushed, filled and pressure tested above its working pressure to ensure it was free from defects and leaks prior to being screeded over.

Ground floor underfloor heating completed manifolds

Each of the underfloor circuits was labelled so that the actuators could be correctly wired to the corresponding room thermostats during the electrical second fix.

First floor underfloor heating perimeter edging

Before the first floor underfloor heating routed gypsum fibrous boards were laid over the acoustic matting, all rooms receiving carpet were edged with 100mm wide by 18mm thick plywood. This allowed the thin 9mm think plywood over boarding to be securely fixed round the perimeter of the rooms ensuring there is no spring in the floor.

The edging further ensured that no pipework was present around the perimeter of the rooms where carpet grippers were installed which could have resulted in pipes being pieced by carpet fitters.

First floor underfloor heating boards

Once all the rooms requiring edging had been completed, the gypsum fibrous routed boards were laid and securely glued in place to the floor decking beneath.

First floor underfloor heating end returns

End returns were installed along the edge of the underfloor boards to allow the pipework to uniformly return upon itself as it traversed the floor.

First floor underfloor heating pipework

With the underfloor boards and end returns in-situ, laying of the underfloor pipework circuits quickly progressed. The installation of the pipework then took place into the pre-routed groves within the boards.

First floor underfloor heating pipework completed

Once all the underfloor heating circuits were installed the accurate and uniform pipe spacing was evident.

First floor underfloor heating pipework tails

Each of the underfloor heating circuits was returned back to the manifold location where they were meticulously cut to the required length and turned through 90° using pre-formed bends to ensure uniform and unkinked pipe before connecting them to the manifolds.

First floor underfloor heating fill and pressure test

Once all the circuits had been connected to the manifolds, the pipework was flushed, filled and pressure tested above its working pressure to ensure it was free from defects and leaks prior to being boarded over.

First floor underfloor heating completed manifolds

Each of the underfloor circuits was labelled so that the actuators could be correctly wired to corresponding room thermostats during the electrical second fix.

Underfloor heating programmable room thermostats

The underfloor heating in each room of the property can be individually controlled by the Heatmiser programmable room thermostats allowing rooms to have different temperatures at different times of the day.

The Heatmiser thermostats are located adjacent to, and at the same height, as the room light switches for a neat appearance and convenient viewing and use. The thermostats are Wi-Fi enabled allowing the system to be controlled both locally and remotely via the internet using smart phones and tablets.

Plant room setting out

The plant room was marked out with where equipment was to be installed prior to commencing.

Plant room pipework clips

Brass munsen rings were then installed ready to receive the plant room pipework.

Plant room pipework in progress

The plant room pipework quickly started to take shape as a result of the accurate setting out.

Plant room buffer tank

The plant room buffer tank, heated by the Air Source Heat Pump (ASHP), provides a store of weather compensated central heating water serving the underfloor heating system.

This ensures that when the Air Source Heat Pump (ASHP) is heating the hot water cylinder, there is no drop in temperature in the underfloor heating system.

Plant room hot water cylinder

The plant room unvented hot water cylinder, also heated by the Air Source Heat Pump (ASHP), provides hot water to all the bathrooms, en-suites, kitchen and utility sinks.

The hot water is distributed via a pumped hot water return system ensuring hot water is instantly available at the hot water outlets.

Filling the air source heat pump system

With the air source heat pump system complete and the underfloor heating fully installed, the installation was then flushed and filled with a mixture of water, glycol and inhibitor.

Freeze protection

The system water was checked to ensure it was protected down to -15°C using a refractometer.

Plant room labelling

Once the plant room installation was complete, all valves were clearly labelled to allow the customer, or anybody working on the system, to be able to easily and quickly identify them.

Air Source Heat Pump (ASHP) concrete base

An external concrete base containing a soakaway for the air source heat pump condensate was formed at the rear of the property to receive the air source heat pump external unit.

Air Source Heat Pump (ASHP) external unit

The air source heat pump was located discreetly to the rear of the property.

Air Source Heat Pump (ASHP) commissioning

With the plant room complete and the distribution system fully installed the final stage of the installation was to commission it.

Operating parameters, such as the weather compensation heat curve and hot water temperature were then set within the air source heat pump controller and a commissioning certificate completed with all the commissioning readings and settings recorded.

Plant room electric metering

The air source heat pump and hot water immersion element used only for legionella pasteurisation of the cylinder were installed with dedicated electrical supplies and meters, clearly labelled.

Having dedicated electrical supplies and meters allows any electrical faults to be easily traced to the area of the electrical system containing the fault and for the accurate electrical usage of each system to be read.

Air Source Heat Pump (ASHP), immersion and underfloor electricity supplies

The dedicated supplies were clearly labelled in the property consumer unit.

Roof prior to PV installation

The property had a standing seam roof. The tolerances of the standing seams were measured once the roof covering had been installed to ensure that the correct standing clamps were procured for the secure fixing of the panels to ensure the calculated wind and slow loads are resisted.

PV cable roof penetrations

Entry points through the roof for the cabling from each of the PV arrays were formed in the standing seam roof beneath the panels to avoid any water ingress.

PV panel setting out

A string line was used to set out each row of clamps to ensure they were exactly in line.

PV panel standing seam clamps

Each of the standing seam clamps was tightened to the seam in accordance with the manufacturer torque settings.

PV panel earth bonding

The panels arrays were earth bonded to prevent the metal roof from becoming live in the event of a fault on the DC panel cabling.

PV panel arrays completed

The completed PV panel arrays sit neatly into the standing seam roof.

PV panel DC string test

Each of the DC electrical strings from the panel arrays was tested for continuity and voltage to ensure there were no electrical faults before the scaffolding was removed.

Photovoltaic (PV) inverter & battery storage

A three-phase SolaX hybrid inverter to maximise the conversion of the DC electricity generated by the PV panels to AC electricity for use was installed in the plant room. The inverter is Wi-Fi enabled allowing the system to be monitored and managed both locally and remotely via the internet when away from the home through the easy to use application. The application facilitates the management and monitoring of the system allowing the customer to access key system data at anytime, anywhere. For example, being able to visualise and compare actual yields with those estimated is essential in ensuring the system is operating at peak performance.

SolaX battery storage was installed in conjunction with the inverter to maximise the self-consumption from the PV panels.

The batteries can also be force charged with cheap rate electricity from the grid during off-peak times when electricity suppliers offer cheaper tariffs. The cheap rate electricity can then be used the following day to power the home and heat pump system.

A completed bathroom

The completed bathroom heated by the air source underfloor heating system.

A completed en-suite

A completed en-suite heated by the air source underfloor heating system.

Curved en-suite shower tray

A bespoke curved shower tray was procured to fit the unique shape of the shower cubicle.

A completed en-suite

A completed en-suite heated by the air source underfloor heating system.

Completed kitchen

The completed kitchen heated by the air source underfloor heating system.

Completed hallway

The completed hallway heated by the air source underfloor heating system.

Completed gallery landing

The completed gallery landing heated by the air source underfloor heating system.

Completed rear of property

The property complete which has all its heating and hot water provided by the new Air Source Heat Pump (ASHP) system and electricity provided by the Photovoltaic (PV) and battery storage system.

Completed front of property

The property complete which has all its heating and hot water provided by the new Air Source Heat Pump (ASHP) system and electricity provided by the Photovoltaic (PV) and battery storage system.