Sustainability and Killynure Green, Northern Ireland

Choice own over 12,000 social housing properties throughout the North and South of Ireland. Killynure Green Phase 1 is the first and only housing scheme in Northern Ireland to achieve Level 5 of the Code for Sustainable Homes (CfCH). This development was the result of an International Design Competition, to design an exemplar social housing scheme that would help tackle climate change through the construction of a zero-carbon development. The scheme of 39 units utilises modern methods of construction, to achieve low maintenance throughout the life of the dwellings.

The scheme engenders a fresh approach to housing design, living patterns and social interaction, with a series of housing clusters layered into the landscape creating a variety of private, semi-private and public open spaces. The overall design of the scheme is aesthetically pleasing with timber, glass and render finishes highlighted with coloured doors. The design strategy hinged round the arrangement of each dwelling cluster to maximise south-facing facades. The use of semi-external wintergardens as a passive design solution, are orientated as close as possible to south to capture free heat, act as a buffer for the residents from the external conditions and complement the internal accommodation. The wintergardens were modelled at design stage to ensure the design optimised solar gains and also provided the required solar shading during the warmer months.

The dwellings feature roofs set at 29 degrees south to achieve maximum orientation for photovoltaic solar collection and employ a prefabricated structural timber system (SIPS), to achieve high levels of insulation and airtightness to minimise energy use. Each house has its own highly efficient mechanical ventilation with heat recovery system, rainwater harvesting with water re-used in WCs, and low flow sanitary appliances. The low heating demand is met by an efficient natural gas boiler, with electricity consumption reduced by the installation of Solar PV systems to generate free electricity. This scheme is designed to use resources efficiently, with energy and CO2 emissions designed to be an improvement of over 60% on current NI Building Regulations. Other sustainable features are an integral water ‘butt’ incorporated into the door canopy to collect rainwater, together with dedicated bicycle storage and facilities provided to encourage recycling. A centrally placed junior playground provides crucial outdoor space for new families and promotes important connections with the wider community.

On the day of handover each tenant attended a training session which allowed them to become familiar with the way their homes have been built, equipment and technology, and how to get the most out of their homes. The dwellings all achieved Secure by Design and Lifetime Homes standards with accessible bathrooms and kitchens.

A performance review of targets was completed 2 years after completion and a follow up 4 year review has recently been completed to evaluate the scheme’s sustainable performance. The review is based on a sample of electricity and solar PV readings from 25 homes, and natural gas meter readings from 34 homes taken in October 2019.

The most notable points from this review of the key performance indicators are:

• Energy consumption continues to be low across this housing scheme, although has risen slightly in the last 2 years (around a 0.5% increase in natural gas and a 5% increase in electricity)
• Energy costs have risen in NI in the last few years, leading to a rise in average energy costs per home from less than £600 to around £750. Other social housing using more typical levels of energy would have incurred a larger cost increase during this period.
• The solar PV systems are continuing to perform well (around 3-10% better than expected) and both income for the Association and savings for tenants have increased due to rising market prices The average home saved around £165/year from their solar PV system.
• Alongside achieving Level 5 of the CfSH, these homes were designed to be zero carbon, which would relate to regulated energy use, although in practice one of the properties actually exceeded this and achieved zero carbon for regulated and unregulated energy use after the first two years.

Killynure Green (Phase 2)

Phase 1 of Killynure Green achieved exceptional sustainable performance and lessons have been learnt which have been incorporated into the design of Killynure Green Phase 2. Choice are currently developing the second phase of homes at Killynure Green, Phase 2 which is the first scheme to meet the new optional energy efficiency standard for social housing in NI. This standard requires homes to achieve a set Fabric Energy Efficiency Score (FEES) within SAP, along with a Band ‘A’ EPC. In achieving this standard, a fabric first approach has been taken, with a focus on insulation, thermal bridging, air permeability and triple glazing. Simple to use, efficient natural gas boilers are being used, along with solar PV systems to support unregulated and regulated energy use, and to reduce overall carbon emissions. One of the lessons from Killynure Phase 1 and other research work carried out by the Association was that a smaller solar PV system is still likely to deliver similar savings for tenants, and so the solar PV systems were able to be reduced for Phase 2. Other recommendations currently being considered are to provide additional information to tenants on the use of their solar PV systems, and also to consider a trial of battery storage in one home.

Tenant feedback has been positive and one tenant recently commented “I moved into this development when it was built and have found that I have much lower energy bills than in my previous home, probably saving around £20 per month. I would rarely have my heating on, but when I do I find that my home heats up very quickly and stays warm… It’s also good to have solar panels on the roof as an alternative form of energy”.