Climate-Proofing Buildings Against Excessive Heat
There are several options to implement climate-proofing of buildings with respect to excessively high temperatures. Such options relate to building design including the use of IT technologies to optimize thermal comfort and those involving building envelopes, including roof, wall, doors, windows and solar control glazing enhancements.
Building design solutions include traditional features of dwellings located in traditionally warm climate countries, such as:
• the building aspect ratio, that is, the ratio between interior space and the external surface of the building that maximizes the dispersion of internal heat and minimizes the uptake of heat through solar radiation.
• architectonic elements such as awnings, overhangs, window shades, porticoes, white or lightly colored external walls and roof.
• the solar orientation of the building, which can minimize the daily exposure of the building to sunlight.
Technical solutions can also play a very important role in mitigating excessive indoor heat. These include sensors that allow fine monitoring of thermal conditions and hence an optimized fine-tuning of air conditioning and ventilation, and even the orientation of shading panels according to real-time insulation conditions. Sensors and digital thermal regulation devices can also be coupled with demand side management measures that help reducing the impact of cooling demand on peak loads when the electrical system is under stress.
A famous example of a building in which a complete package of state-of-the-art solutions has been applied is The Edge office building in Amsterdam completed in 2014. The building envelope includes dynamic windows, automatic shades and displacement ventilation. A total of 28,000 sensors track movement, lighting levels, humidity and temperature, which allow an immediate and more efficient response to energy needs, such as automatically switching off heating, air conditioning and lighting in unused areas. Moreover an app provided to those working in the building allows them to adjust temperature and lighting levels around them using their smartphone. Cooling and heating involves the use of a heat exchanger that transfers heat in the desired direction between the building and an aquifer beneath it.
The organization of the spaces in the proximity of buildings also matters since the deployment of vegetation can be used to increase air flow and reduce the impact of solar radiation. Examples include:
• Use trees to provide shade to cool roofs, walls and windows.
• Landscape around your home so that it is cooled by evapotranspiration, the release of water vapor from the soil and plant surfaces into the atmosphere.
• Position trees strategically to funnel summer breezes toward your home to facilitate natural cooling.
• Abundant plantings can increase humidity, thus increasing comfort levels on excessive heat days. But avoid locating thick plantings so close to the house that they prevent natural airflow through building openings.
The technical features of the building envelope are crucial for its ability to control indoor temperatures. The materials of which the envelope is built and their mass in fact determine how quickly temperature differentials between indoors and outdoors are compensated. Thick-wall traditional buildings in the Mediterranean, for instance, require much less air conditioning than modern buildings. Alternatively, the use of materials with high thermal resistance can reduce the heat that enters the building. This option is particularly interesting for retrofitting existing building with insulation layers that compensate for the poor thermal properties of the original building materials.
Also, the use of mechanical or natural ventilation, or storing cold in materials with high thermal mass like tiles or stones, reduces the need of air-conditioning. Cold storage can be coupled with a heat pump to increase the flexibility in the deployment of cold air. A conventional heat pump usually relies on the electrical grid to drive the system. A more cutting-edge solution would rely upon a geothermal system, exploiting the differential between underground and surface temperatures.
Adjust Indoor Humidity Levels
Adjusting indoor humidity can have a strong impact on perceived temperatures and ultimately on thermal comfort of the occupants of a building. Tips for managing home humidity include:
• Close the doors and use the AC.
• Change air conditioner/furnace air filters.
• Fix leaky pipes and faucets.
• Keep surface areas dry.
• Use ceiling fans to help with air circulation.
• Air dry clothes or make sure dryer is vented outdoors.
• Weather-strip doors and windows.
• Use your outdoor grill or BBQ pit.
• Keep interior doors open to increase ventilation.
• Run the dishwasher at night.
• Use bathroom and kitchen exhaust fans.
• Decorate with humidity-absorbing plants like Boston fern or English ivy.
• Use a dehumidifier.
Roofs are also important heat exchange surfaces, and their design can help reducing significantly the energy needs of a building. Green roofs, for instance can significantly help reducing the heat island effect in cities by naturally cooling building surfaces through the action of water and vegetation. A cheaper but also effective option is painting roofs white or in utilizing light, highly reflective colors that bounce back solar radiation. Top grade white roofs reflect 80% of solar energy; black roofs on the other hand reflect only 5% to 10%.
These described measures focus on coping with excessive heat. This does not automatically imply that all of them can also help conserving heat in winter. However, increasing the insulation of the building envelope and increasing the thermal mass can work to both cool the building in summer but also to cool the building in winter.
For Further Reading:
• The Department of Energy has published a list of tips for keeping homes cool without resorting to mechanical air conditioning. The link is: https://www.energy.gov/energysaver/heat-and-cool/home-cooling-systems
• The website Millionacres.com has published a contributing article at: https://www.millionacres.com/real-estate-market/articles/death-valley-heat-wave/
• Energy Monster has published a checklist to prepare your household for extreme heat at: https://myenergymonster.com/ma/10-ways-to-prepare-your-home-for-a-hot-summer/