Several methods and tools have been developed over the past two decades aimed to evaluate energy consumption in buildings; in response to the implementation of regulations on energy use in buildings. Evaluation of energy performance for buildings has been carried out using benchmarks. These benchmarks are usually as a result of building audits and surveys to establish what is typically accessible or extant conditions (Vaezi-Nejad, et al., 2003) (Krarti, 2012). The overall understanding is that if the current situation is responsible for climate change or deemed unsustainable, then the goal is to design that which consumes less energy and produces a lower carbon emission.
Hence, the typical can be well thought-out as a benchmark or a worst-case situation. Having set these benchmarks, the assessment process requires the designed building to achieve minimal requirements set in the benchmarks or more.
Energy tools are software and methods used to evaluate building design. These energy tools give a real building simulation where the energy consumption can be evaluated before the building in built.
The purpose of using such tools for design is to enhance building performance as it produces predictions or performance based on the building model. This software replicates the dynamic and intricate interactions between the building with its environment and installations.
“The design analysis involves the ‘creation’ of a behavioural model of a building design, and analysing the outputs of the simulation runs. Models are developed for a problem domain by reducing the physical entities and phenomena in that domain to idealized form on a desired level of abstraction, and formulating a mathematical model through the application of conservation laws” (Augenbroe 2000).
These days, computational advancements brought about faster processors and easy to use graphical interfaces, hence, stimulates the extension of various energy tool applications, which extended from research laboratory to commercial use in offices. As Hiller and Schuler (1999) acknowledged, that energy tools are useful to check the practicability of low energy strategies use in building design. Using these tools, the impacts of design decisions made can be evaluated and their cost consequences assessed accordingly. Also, Hong, Chou et al. (2000) classified energy tools into detailed simulation programs (DSPs) and design tools (DTs). DSPs are complex and normally integrate computational techniques such as finite differences, finite elements, response factors and transfer function for building load and energy calculations. While DTs are more purpose specific and are commonly used at the early stage of design because they involve the input of less and simpler data.
In some literature, they affirm that the use of computer simulation by building experts is now considered a routine practise (Hong, Chou et al. 2000). Thus far, it might be effective for some particular places, but definitely not for Nigeria. Any intention to produce integrated energy tools reveals an extremely complex issue, such as the “International Alliance for Interoperability” (Bazjanac 1999) and the “COMBINE Project” (Kenny 2001). Even though this approach improves the use of energy tools, the approach can still only evaluate a design when it is very detailed. In these terms, the majority of energy tools are orientated to check assumptions in detailed design.