Key Features

  • Our current Standard Variable Rate is 4.65%
    Representative example:
    A mortgage of £225,700 payable over 25 years on our  variable rate, currently 4.65%, would require 1 monthly payment of £1,621.10 and require 298 monthly payments of £1,276.06.
    The total amount payable would be £382,811.98 made up of the loan amount plus interest (£156,186.98) and a mortgage application fee of £300 and a valuation fee of £625 (assuming a purchase price of £350,000).
    The overall cost for comparison is 4.80% APRC representative
  • We’ll consider lending up to four times joint or sole income subject to loan-to-value and an affordability assessment
  • Energy-efficient homes are rewarded with discounts off our Standard Variable Rate - see details below of how our C-Change sustainable homes discounts work
  • Mortgages are available on a repayment, interest-only or part (repayment) and part (interest-only) basis, subject to eligibility
  • Interest-only and part interest-only mortgages are subject to an acceptable repayment vehicle
  • You can borrow up to 80% of the property’s value on a repayment basis, or up to 75% interest-only or part (repayment) and part (interest-only)
  • An early repayment charge may be payable if you repay all or part of your mortgage within the first two years
  • A non-refundable mortgage application fee of £300 is payable in addition to a mortgage valuation fee
  • We're currently focusing on properties that are aiming for Passivhaus or EPC B (SAP rating 85+) or above
  • A maximum mortgage term of 30 years is available, subject to eligibility
  • Borrowers must be aged 18 or over.  This mortgage is only available to UK residents.

If your project requires planning permission or listed building consent, this will need to be in place before we lend any mortgage funds.

What we lend on

 We are experts in providing residential mortgages for property  conversions of non residential buildingsWe don't have a 'tick box' approach to assessing projects – in many instances, we'll welcome projects that standard lenders may not accept. We will consider:

  • Derelict barns, cow sheds
  • Redundant garages
  • Windmills
  • Water Towers
  • Churches and Chapels
  • Oast Houses
  • Redundant pubs (public houses).

Our mortgages are available in the UK (England, Scotland, Wales and Northern Ireland).

Our approach to lending during your conversion project
  • We release funds when valuations show your conversion project has increased in value
  • Our Standard Variable Rate applies during the works and our discounts are applied from the date we receive evidence that the conversion works have been completed and the energy rating required has been achieved.
Our standard of service

The Financial Conduct Authority (FCA) has laid down detailed rules about the service we must offer on regulated residential mortgages. Under these rules, we will provide you with advice and a recommendation on which of the Society's products is most suitable for you, based on your needs, preferences and affordability.

Further information


Rated as an ethical Best Buy for our mortgages and savings

For new builds and existing energy efficient homes: C-Change sustainable homes discount

Our C-Change sustainable homes discount applies to new and existing energy efficient homes and extensive retrofits using the Passivhaus EnerPHit methodology. Once your build is complete, you need to provide an Energy Standard certificate and Architect/Building Control certificate for us to apply the Sustainable C-Change discount. The discount is applied from the date we receive all the required documentation and is based on the Energy Standard rating the property achieves.


Energy StandardRatingsSVR (Standard Variable Rate)Discount %Variable Mortgage Rate
PassivhausPassivhaus4.65%1.25%3.40%. The overall cost for comparison is 3.50% APRC
PassivhausEnerPHit or
4.65%1.25%3.40%. The overall cost for comparison is 3.50% APRC
PassivhausEnerPHit (PHPP modelled)4.65%0.75%3.90%. The overall cost for comparison is 4.00% APRC
Energy Performance Certificate (EPC)A or above4.65%0.75%3.90%. The overall cost for comparison is 4.00% APRC
Energy Performance Certificate (EPC)B (SAP rating 85+)4.65%0.50%4.15%. The overall cost for comparison is 4.30% APRC
Association for Environment Conscious Building (AECB)Standard4.65%0.75%3.90%. The overall cost for comparison is 4.00% APRC
Conversion FAQs

Does Ecology require planning permission for my conversion project?

Yes. We need at least outline planning permission to start the application process and detailed planning permission before the mortgage is released.

What information do I need to progress a mortgage application?

You’ll need to have a specific property conversion in mind which needs to be supported by detailed plans, including a breakdown of material and labour costs and an indication of the Energy Standard you are converting to. We’re currently focusing on conversions that are aiming for Passivhaus or EPC B (SAP rating 85+) or above.

What deposit do I need for my conversion project?

You need a 20% minimum deposit to buy the property and a further 15% – 20% of total conversion costs to start your project.

Do I still need a deposit for my conversion if I already own the property and have planning permission?

No, you don’t always need a deposit; we can lend based on the value of your property to start the conversion, providing you already own the property and it’s mortgage-free. Also, we can help you repay any outstanding finance on the property if you need it.

Do borrowers who are planning to convert their property need to show how they plan to improve the property’s energy efficiency?

Any project we support needs to show planning details of the proposed conversion with an indication of the Energy Standard you are converting to, and how the project costs are expected to be funded with savings and mortgage finance. We don’t just lend to purchase the property.

How long do I have to complete the conversion?

Subject to planning constraints, we allow a maximum of 2 years for you to complete the conversion, although we encourage you to complete earlier to benefit from our C-Change discount (C-Change sustainable homes or C-change energy improvement). The applicable discount is applied to our Standard Variable Rate when we receive evidence that the work has been completed and the Energy Standard rating required has been achieved.

Do you offer stage payments for a conversion?

Yes, although the Ecology conversion mortgage does not release payments at set construction milestone stages. We release funds as and when the conversion progresses and release up to a percentage of the increased value of the property.

Can I have an interest-only mortgage during the conversion phase?

We offer an interest-only mortgage only when you have a qualifying repayment vehicle to support this for example an established ISA, endowment policies or Pension Plan.

Does Ecology require a particular build warranty on completion of my conversion?

A build warranty is not a mandatory lending requirement of our mortgage and we are happy with a Building Regulation Completion Certificate. However, if you wish to take out a build warranty for the completion of the property then this is acceptable to the Society.

Does the conversion property have to be my main residence?

Yes, although we do offer a buy-to-let mortgage. Please bear in mind that we don’t offer mortgages for second homes, holiday homes or homes classed as mobile planning.

C-Change discounts explained

As a building society with a unique mission to build a greener society, we lend on projects and properties that support our aims through their reduced impact on our environment. Making your home energy efficient is a major way you can support tackling climate change – while saving on your energy bills.

We reward borrowers whose properties are energy efficient (therefore have lower carbon emissions) with our C-Change discounts off our Variable Rate which helps them save money on their mortgage. We call our discounts ‘C-Change discounts’ simply because we’re aiming to make a ‘sea-change’ of difference to our climate with each property or project we fund.

The level of our C-Change sustainable homes or C-Change retrofit discount that applies is based on the Energy Standard rating achieved on the self-build, renovation or conversion when the work is completed. Our C-Change energy improvements discount is based on the qualifying energy measures being installed. The discount is applied from the date we receive evidence that the work has been completed and if applicable the Energy Standard rating required has been achieved.