Property: Going green without slipping into the red

Loft insulation or cavity Wall Insulation from just £109 or £218 for both - a saving of £250 compared to NP's standard offer.

EDF ENERGY

· Free home energy survey.

· Savings of up to £475 on cavity wall insulation.

· Savings of up to £365 on loft insulation.

· Hot Water Tank Insulation for just £10.

BRITISH GAS

· Free cavity wall insulation to customers over 60 or on income- or disability-related benefits.

· Free loft insulation to customers over 60 or on income or disability benefits.

Reader competition

The Observer has teamed up with EST to offer five readers the chance to have their homes examined - inside and out - to see how green they are.

You will receive a personalised report revealing what you are and aren't doing to reduce the environmental impact of your home. Accompanying this will be top tips on where improvements could be made and how much money and carbon you could save by following EST's advice.

Also included in the prize is a set of thermal images of your home and a 'heat loss' survey worth over £500. Thermal imaging captures heat and converts it into a photographic image that displays temperature differences. It will identify how and where heat is escaping from walls and windows, and reveal any damp tracing, along with the measures you can take to stop this, such as cavity wall insulation.

To enter, simply send your answer to the following question along with your name, address, telephone number and a photograph of your home to: Thermal Competition, PO Box 4171, London, W1A 6YH.

QUESTION 'What does thermal imaging display?'

Terms and conditions

1. The prize is a Home Energy Check (an energy audit of your home), which will be undertaken by the Energy Saving Trust (EST), and a thermal imaging report, which will be outsourced by EST. Five identical prizes are on offer.

2. The prize offers advice on how to improve the energy efficiency of your home. The prize does not include the implementation of any of the suggested measures.

3. All thermal imaging will be undertaken at an agreed date in either September or October 2005, as cold temperatures and dark light are required for this photography.

4. Only one entry per household will be accepted.

5. The prize is only valid for residential properties within England, Northern Ireland, Scotland and Wales.

6. The competition is not open to residents in the Channel Islands or the Isle of Man.

7. Entrants residing in flats and apartments are not eligible for the prize. This is because properties must be thermal imaged in their entirety to effectively demonstrate temperature differences. EST therefore reserves the right to judge the suitability of the property for the prize.

8. The prize is non-transferable and no cash alternative is available.

9. The winners will be picked at random by EST. The decision of the judges will be final and binding and no correspondence will be entered into.

10. The winners must agree to participate in publicity for the prize.

11. By entering this competition you agree to receive further information from EST.

12. Entry into the competition is free and no purchase is necessary.

13. Employees, ex-employees (and their families) of EST and all agencies connected to this contest are not eligible to enter.

14. The closing date for entries is 19 June 2005.

15. The winners will be notified by 3 July 2005.

16. All prizes must be accepted by 14 October 2005.

17. Entrants will be deemed to have accepted and agreed to be bound by these terms and conditions.

18. Promoter: EST