The thermal storage ability of materials (i.e. their thermal mass) can play a huge role in a building’s performance. Materials with high density, such as concrete, bricks, and tiles, have a high thermal mass. Placed correctly in correlation with a passive solar design strategy, these materials can moderate indoor temperatures through delayed heating and release, but used poorly they can exacerbate climate extremes and be a huge energy and comfort liability.1 In most climates with significant cooling loads, thermal mass can be used to decrease energy needs and increase comfort, as long as daily temperature variation is significant.2
Higher surface reflectivity can increase a space’s average daylight factor by as much as 50%3 and reduce energy use of a lighting system by up to one-third.4 However, material reflectance values are not always intuitive, and properly locating various reflectance values to distribute daylighting requires close study. As a general rule of thumb, standards suggest that reflectance values for floors should be 20-40%, walls should be 50-70% and ceilings should be the highest at 60-80%.5 Additionally, light-colored materials can reflect light and reduce heat gain. White roofs can cut summer cooling costs by up to 20%.
Occupant indoor environmental quality (IEQ) surveys show that poor acoustics are the greatest cause of dissatisfaction in LEED-certified office buildings.6 Research proves that it takes an average of 15 minutes to regain concentration after being distracted from a difficult task.7 Common mistakes leading to poor acoustics include:
- Eliminating ceiling tiles without considering acoustic impact
- Not compensating for quieter more efficient HVAC systems
- Assuming that wall panels will block voices
As Steward Brand’s shearing layers diagram points out, the building materials that we interact with are the ones with the shortest lifespan. The internal materials of a building last approximately 3-30 years before they must be replaced, as they put up with the most wear and tear from occupant use. The longer these materials last, the more time the raw materials, embodied energy, and environmental impacts invested in the product have to amortize.8 Also, they are typically lower maintenance, and look more attractive for longer. Knowing areas of high impact and predicting a reasonable service-life target will help select materials of an appropriate durability.