| TADEA |
| Tait Consulting |
| Taylor Woodrow Technology |
| TCP |
| Tebway Ltd |
| Tenant Services Authority |
| Tenet Education Services |
| Tesco |
| The Carbon Trust |
| The ENDS Report |
| The Energy Advice Service (TEAS) |
| the Environment Centre (tEC) |
| The Financial Explorer (Southern) Ltd |
| The Institute of Home Inspection (IHI) |
| The Lighting Association |
| The Passivhaus Network |
| The Scarab Trust |
| The Social Marketing Practice |
| The UK Carbon Census |
| the useless energy company |
| The Wise Group |
| The Wrekin Housing Trust |
| thegreenassociates |
| Thermal Solutions |
| Third Stone Ltd |
| Thornhvac |
| Three Valleys Housing |
| Timeguard Ltd |
| Toshiba Information Systems UK |
| Total Heating Solutions Ltd |
| Town & Village |
| TPAS |
| Trident Manfacturing Ltd |
| TVEC |