Case Study - Plot 74 at Oakwood/Coed Derw, Conwy

The escalating climate crisis is at the forefront of every UK house developer’s mind.  With new and existing housing accounting for 9% of Welsh greenhouse gas emissions, Beech Developments are no exception and strive to be one step ahead to reduce carbon emissions in our homes.  In order to do so, Beech have been exploring new methods to significantly lower the amount of energy used to power and heat our homes.  The national ban to supply gas boilers to new homes in 2025 has been a welcomed announcement from the UK Government, however Beech believe that we shouldn’t have to wait that long to begin moving towards low-carbon heating.

A new Beech homeowner allowed us to start this crossover sooner on our Oakwood development in Conwy.  The energy conscious homeowner gave a brief to the team for a low-carbon, energy efficient home with no reliance on gas for heating or hot water.

An air source heat pump (ASHP) was the chosen method of heating due to the many benefits.  The ASHPs work by absorbing heat from the air to heat the home and provide hot water.  The air is absorbed at low temperature into a fluid which passes through a compressor.  The temperature increases and the heat exchanger transfers the heat to the heating and hot water circuits in the home.  The chosen model installed in the home was the Vaillant aroTHERM 7KW Split air source heat pump.  

Vaillant has been setting the standard in the heating market since 1874 by continually developing products that revolutionise the industry.  Their innovative solutions are still setting the standard in the heating marketplace. They produce a comprehensive range of renewable technologies designed to utilise sustainable sources of energy. 

The key features of the aroTHERM Split are;

• Sound Safe System with exceptionally quiet operation allowing for flexible siting options 

• A+++ ErP rating- Highly efficient for lower running costs

• Modulating performance which automatically adjusts power to maintain comfort and optimise efficiency

• Flexible energy solution allowing other appliances such as PV/ battery storage to be linked to reduce running costs even further 

• App based proprietary control with installation wizard for easy set-up and weather compensation as standard, all controlled via a mobile device.

External Compressor 

Heat Exchanger 

The next aspect Beech looked at in order to provide a low energy home with the addition of lower fuel costs, was the installation of solar battery storage.  For a number of years our homes have been provided with solar photovoltaic (PV) panels as standard.  This has benefitted the homeowners as they have been able to generate their own electricity, even on cloudy days, demanding less energy from the grid and reducing electricity bills, but they have also been able to recover money from the Export Tariff. This is a bonus payment for every kilowatt-hour of surplus electricity the system exports to the electricity grid.

With PV’s generating free energy during daylight hours, a time when the majority of homeowners are out at work, homeowners are unable to take full advantage of the PV’s unless they have a solution to store the energy.  Therefore, the installation of a battery storage was used to give the homeowner increased energy independence and in return lower electricity bills.  The excess PV power is stored in the battery, located in the garage, and can be used when needed.  The chosen system installed was the SolarEdge system along with a 10kWh LG Chem battery store.

The SolarEdge Smart Energy Management solution integrates solar energy production with battery storage and home automation (immersion heater controller/ EV Charger/ smart relays & switches), all under the control of a single SolarEdge PV inverter.  The SolarEdge DC-optimized system provides substantial benefits including more PV power, higher system visibility and advanced safety features.

The system comprises of:

Inverter - The brains of the PV system, the SolarEdge inverter has a fixed input voltage and is responsible only for DC to AC conversion. 

Power Optimisers - Connects to each solar panel on the roof enabling them to perform independently, providing greater energy harvest, enhanced safety, and constant feedback from each panel.

StorEdge Battery Controller - Store unused PV energy directly on compatible, high power DC batteries from LG Chem.  StorEdge is a DC-coupled solution allowing for higher system efficiency.  A 10kWh LG Chem storage battery will store excess solar PV energy for use when the house demand is greater than the energy produced from the solar PV system.  This stored energy will be used before any electricity is taken from the grid.

Immersion Heater Controller – Will automatically send any surplus generation (that would be exported back to the grid) to the immersion heater element.  This means that the majority of the water heating can be achieved by surplus energy, therefore saving on the cost of the primary water heating source.

Electric Vehicle (EV) Charger – A 32A (7kW) EV charger that can be set to use only surplus solar generation to charge a vehicle.

ModBus Energy Meter – this monitors the import/ export and generation of electricity and informs the “smart devices” when there is available surplus energy.  The data is displayed in the online monitoring portal.

Online Monitoring Portal – Displays historic and real-time energy generation data in an online portal and a mobile phone app.  A full early diagnostic and fault-finding system is included in the portal, clearly showing any faults and allowing the SolarEdge engineers to investigate remotely.  This service is provided free of charge for 25 years.

The SolarEdge system provides a number of benefits to the homeowner including:

• Full monitoring with early warnings of any potential issues as soon as detected with email alerts to the homeowner and the installer.

• Surplus solar energy can be directed to any SolarEdge smart home device in order of priority set by the homeowner through the monitoring app.  For example, priority could be given to the immersion heater to use first, then the car charge, with all extra surplus then directed to be stored in the storage battery for later use.

• EV charger offers a trickle charge mode using solar excess only, or can be set to boost mode using both solar and grid for 2.5x charge rate.

• Depending on hot water usage the immersion controller should heat up the hot water up to temperature for most of the summer months.

• Profiles can be set so that the battery can be charged at night time on a cheaper rate of electricity cost – this will then be discharged back into the house when needed during the day (at peak cost times) further reducing running costs by taking advantage of off-peak energy rates.

Combining the systems allowed us to fulfil the homeowner’s brief, creating a beautiful home with the superb benefit of low carbon emissions and reduced energy bills, with complete unreliability on the gas grid.  Using the battery storage to reserve the renewable energy generated by the PV’s, the homeowner has the freedom to use the energy when it is most beneficial for them, as well as providing power for use of an electric vehicle.

The above standard levels of insulation and exceptional workmanship allowed the home to achieve an EPC rating of 99%, band A (92 plus).  To put this into perspective, the average EPC rating in the UK is band D (55-68) with new build properties tending to have higher EPC rating than the average.  In Wales, homes have become significantly more energy efficient over the last decade, with social housing having the highest percentage of dwellings in EPC bands C or above.  Only 7% of dwellings in Wales use at least one type of renewable energy, with most dwellings (82%) relying on gas to heat their homes with condensing-combi boilers, the most common boiler type (66%).

Beech Developments continued measures and actions to help tackle climate change, by changing the way we heat and power our homes, will continue to keep down household energy costs now and in the future for all our homeowners.