In order to make the understanding of data universal the International System was developed. This system standardized measurements for nearly everything that scientists are interested in measuring. Here are a couple of examples: meters, joules, seconds and watts.
The International System of Units (SI, abbreviated from the French Système international (d’unités)) is the modern form of the metric system and is the most widely used system of measurement. They are adopted to facilitate measurement of diverse quantities.
These are the measurement units that you will need to use in your energy science fair projects.