Net-zero energy buildings are important for reducing energy consumption in cities. A study looked at a residential building using solar energy and special glass to save energy. They used computer models to test different energy systems and found that a mix of solar panels, solar thermal technology, and special glass is the best option. This system saves the most energy and costs the least. However, in Singapore, these systems are not cost-effective yet. But a mix of solar panels, solar thermal, and special glass can still make a building produce as much energy as it uses.