Cullen Community Zero Carbon Study

The team selected by tender consisted of three companies

Collective Energy are a specialist division within Collective Architecture, established in 2020, to offer key services and advice around how to make buildings, places, processes and communities more sustainable and effective. They were instructed to look at the fabric of the building.

KJ Tait Engineers were instructed to investigate low/zero carbon technologies. Their study investigated the economic and technical viability of decarbonising the heating system by installing heat pumps, both air source and ground source and biomass. A small wind turbine was also assessed to potentially provide the majority of the buildings electrical load.

Power Circle were instructed to look at the renewable technology and battery storage options and act as project co-ordinators.

Following a very detailed study the recommendations from the three companies are summarised below.

Recommendations from Collective Energy

Zoning

The existing building is effectively divided up into 2 zones based on the heating system used for space heating.

For the benefit of the energy analysis and the proposed future retrofit works it was agreed that the building be subdivided into a number of zones. This would facilitate planned grouping of services controls as well as parcel out areas for focussed retrofit works.

In order for these services interventions to be implemented in efficient manner that delivers optimum energy efficiency the overall heating demand of the building needs to be reduced significantly. It is therefore imperative to develop an energy strategy that employs a fabric first approach to reducing energy demand coupled with the new energy efficient Zero Carbon heating, and power solutions being proposed.

In order to obtain maximum yield from any interventions carried out in the short term a focus needs to be placed on the following areas of improvement:

– Insulate the external fabric to the highest possible performance

– Change windows & doors to triple glazed units

– Improve air tightness

– Mitigate thermal bridges wherever possible

– Improve ventilation, shifting to Mechanical Ventilation with Heat Recovery (MVHR)

– Improve heating and hot water systems

– Improve lighting systems

– Generate renewable energy on site

RECOMMENDATION from KJ Tait Engineers

We would recommend that GROUND SOURCE HEAT PUMPS (GSHP) are installed on site due to the following factors:

• • Improved Coefficient of Performance compared to AIR SOURCE HEAT PUMPS ASHPs when operating in the peak winter conditions when generating both heating and hot water
• • Opportunity to complete works on a phased basis
• • Greater potential for funding streams

As the electricity grid greens further towards zero carbon, GSHPs would be seen as a zero-carbon generating technology. Due to the lower flow and return temperatures of a heat pump system, it would be advantageous to carry out some fabric works to ensure that the heat pump performance is maximised.

Recommendation from Power Circle.

In order to decarbonise the buildings electricity supply, a PV array should be installed over the south facing roofs. It is apparent that this would generate more electricity than the building would require, particularly over the peak summer period. Therefore, battery storage should also be incorporated. This will ensure that electricity generated can be used wholly on site and that the building can benefit from a night electricity rate by charging the battery for use during the day.

Conclusion

The study has been shown that it would be feasible to make the Cullen Community centre a Zero Carbon building.

For this to happen, it will require a lot of fabric improvements to be done to the building before we change over to use ground source heat pumps.

A lot of the cost will be for insulation, whilst other required activities will receive funding.

All types of insulation are required, and that is where we need your help to make this happen. Any donations of insulation or cash for our crowd funder will help towards making the Cullen school of 1876 a building fit for a zero-carbon world.

Our aim is to make it a zero-carbon building on the 150th anniversary of its opening in 2026 and make it a building fit for the community for another 150 years.