Energy Efficient Specialists Custom Builder. We specialise in building to high energy efficient standards and working with our clients from the beginning of the design phase to make sure your project is always on budget and delivered on time. Working with Enduro Builders means receiving a detailed fixed price on your job and enjoying open and informative communication with us. All of this is backed by our online project management system which you have exclusive access to throughout the project. No other builder is able to provide the level of communication and service.