Easy Breezy - Heatwaves

When designing the ambiance in your home, the temperature should be top of mind. A house maintaining a temperature of 78°F during summer and 68°F during winter is considered a comfortable and energy-efficient home. 

By maintaining a comfortable temperature, we don't mean with the help of AC, furnace, and fireplace year-round, but rather a house designed and built so it can maintain comfortable temperatures with minimum dependence on cooling and heating systems.

Great ambiance and comfort can be achieved by investing in good household insulation, air tightening, and efficient HVAC solutions, which in return, also yield considerable financial savings. 

Such implementations will also transform your home into a more sustainable one: resilient in the face of extreme weather events and power outages, and eco-friendly with reduced/no negative impact on the environment. Many strategies for extreme temperatures are both climate mitigation strategies and climate change adaptations.

 

Key strategies we will cover in this blog post:

• Building Envelope / Passive Strategies 
  • Foundation, Wall, and Roof Insulation (beyond code)
  • Stack and/or Cross Ventilation
  • Air and Water Barriers
  • Passive design (see our “passive house” blog for further details)
• Cool Roof 
• Design with Plants
• Energy Management Systems
• Energy/Environmental Modeling 

 

Outside Temperatures and Your Home - A Refuge From Extreme Weather

According to the National Oceanic and Atmospheric Administration (NOAA), “the year 2020 was the second warmest year in the 141-year record. The five warmest years in the 1880–2019 record have all occurred since 2015, while nine of the ten warmest years have occurred since 2005. The year 2020 marks the 44th consecutive year (since 1977) with global land and ocean temperatures, at least nominally, above the 20th-century average.”

According to the U.S. Department of Health and Human Services Centers for Disease Control and Prevention (CDC), extreme heat events “trigger a variety of heat stress conditions, such as heat stroke.” While heatstroke is the most serious heat-related illness, as it can lead to death, higher temperatures have also been linked to respiratory problems. One reason for this is that “higher temperatures contribute to the buildup of harmful air pollutants.” 

According to NOAA, extreme heat causes more deaths than any other extreme weather event.

Whether you are designing a new home or renovating an existing one, there are many solutions that you can adopt to reduce the risks of extreme temperature events and can improve the overall resilience of your home to better cope with extreme climate conditions. By adopting the following strategies, your home can be your refuge even in places that are predicted to be too hot to live in within the coming decades. 

Note that we are covering the fundamentals of these strategies and provide pointers to some solutions that are available in the market, but, by no means, is this an exhaustive list. There are many more products and solutions out there.

 

Building Envelope / Passive Strategies 

Foundation, Wall, and Roof Insulation (beyond code) 

Proper insulation of crawl spaces/basements, walls, and the roof of a building help mitigate the risk of overheating by reducing conductive gains through the envelope and roof. This strategy can reduce interior air temperatures, peak electrical demand, and annual cooling requirements. 

Research done at the urban level in London showed that insulation levels considerably impacted indoor temperatures. With combined retrofitting of roof insulation and window upgrades, daytime living room temperatures were reduced during the warmest continuous 5-day period. Conversely, internally retrofitted walls and floors tended to increase daytime living room temperatures. 

Insulation has many advantages beyond making occupants more comfortable, such as: improving air quality, reducing outside noise, saving energy with direct returns on your investment through substantially lower energy bills, as well as an appreciation of your home value.

There is also a green angle, well, actually two. First, the reduction of energy use will lower the impact of your home on the environment. Second, some of these insulation solutions are also made of green materials and processed in a green fashion, which means you can further reduce the impact of your home on the environment, not to mention, improve the overall health of your home’s occupants (by not using chemicals or other health-hazardous materials).

Some of the best green and resilient insulation materials are cotton, castor oil-based, soybean-based foam, and sheep's wool insulation. 

The top manufacturers of such solutions can be found here in eampact, and also in Home Depot, Lowes, Amazon, and local shops (which we support!). They are:

• Rockwool is one of the leading and top-quality manufacturers of wool-based insulation solutions.
• Huntsman (previously known as Demilec) makes some of the best Bio-based foam insulation solutions.
• Bonded Logic makes some of the most advanced cotton-based insulation materials.

 

SPOTLIGHT: Blue Jeans Go Green program is a non-profit organization that collects denim (made from cotton) and recycles it back into its natural fiber state and transforms it into something new - insulation. They have teamed up with Bonded Logic and a portion of their UltraTouch™ product is contributed to Habitat for Humanity affiliates and other building organizations.

Stack and/or Cross Ventilation:

These strategies provide passive methods to cool the building on warm days and allow occupants to control the indoor air temperature in response to changing exterior climatic conditions. In the event of a power failure, these strategies may allow occupancy in a building even if there is no mechanical / active cooling present. 

Stack ventilation relies on the buoyancy of warm air to remove heat from space by allowing hot air to rise and exhaust out of the space, while cross ventilation relies on the air pressure from the wind to remove heat from a space. 

Natural ventilation increases heat loss in the summer and provides a cooling benefit during the daytime. In some climates, particularly those with low relative humidity, buildings can be designed to rely entirely on natural ventilation, while in climates with higher humidity, natural ventilation may be more practical as a backup cooling strategy, and can be used during power outages as a passive survivability measure. 

For further reading on these two concepts check this out. 

 

Air and Water Barriers

The exterior of the building should have a continuous air barrier to prevent water and wind from blowing into the wall cavity to prevent mold and mildew problems and allow the effectiveness of the energy performance. According to the Climate Ready District of Columbia (CRDC)’s Resilient Design Guidelines, “with rising temperatures and potentially higher precipitation in the future, the control of air and moisture flow into the building envelope is particularly important to ensure building durability”.

 

Passive Design: 

Passive House Institute (PHI) defines a passive house as a “building standard that is truly energy-efficient, comfortable, and affordable at the same time. Passive House is not a brand name, but a tried and true construction concept that can be applied by anyone, anywhere.”

In other words, a passive house is a design and construction of a house that eliminates the need for active air conditioning and heating systems. A passive house will maintain the best comfort for its occupants by keeping the house cool on the inside during summertime, and warm during winter without the use of HVAC systems. In addition, a passive house will provide its occupants with fresh, healthy air.

On top of its efficient, environmentally friendly attributes, we consider the "passive design" to be a resilience strategy. The ability of such a design to provide an alternate, passive form of space heating and cooling in the event of a power outage, eliminates the reliance on the electrical and natural gas grids. This is a fundamental strategy for homes in risk zones with extreme weather events where power outages occur while the outside temperatures and/or air quality are extreme and hazardous. 

Passive design is achieved by implementing several solutions: tight insulation, airtightness, ventilation, windows location, materials, and thermal bridging. It is challenging to retrofit an existing house to become truly “passive”, however, adopting these solutions can yield a safer, more resilient house, amid power outages and extreme weather conditions.

To further learn about the passive house method, check our blog here: What is a Passive House.

 

Cool Roof 

Select a light-colored roof with high solar reflectance and high emissivity.  A reflective roof surface reduces cooling loads in the building and the urban heat island effect. Cool roofs have also proven to boost the performance of rooftop solar systems.

The Cool Roof Rating Council (CRRC) developed a rating program with which companies can label roof surface products with radiative property values. the CRRC lists the measured radiative property values on the Rated Products Directory. Westlake Royal Building Products is an example of a manufacturer of products rated by CRRC. Their cool roof system allows for reducing excess solar heat gain. 

 

Design with plants

Plants and vegetation reduce the temperature of the building by providing shade, absorbing heat, and evapotranspiration. 

By incorporating plants in the facade of the building, you are adding insulation and therefore, reducing the energy usage in the home and increasing the energy efficiency. Note that the design should consider the structural load of the plants on the building and that it can be difficult to maintain.

 

Energy Systems

The strategies for climate change adaptation in this section focus on:

• Improving the performance of building mechanical and electrical systems to respond to temperatures
• Improving the efficiency of building mechanical systems to allow increases in capacity without reducing total performance

The size of an HVAC system, and its associated energy use, are estimated using data that provides various annual climate averages based on past weather data. 

Designing even the best cooling and heating systems based on historic weather data will make building systems vulnerable to future changes in climate. 

A building’s energy use will increase if climate extremes become the norm. Air conditioning can reduce thermal discomfort and health risks of overheating dwellings, but it entails considerable energy consumption which may contribute to the urban heat island effect. It is also dependent on an uninterrupted power supply during periods of hot weather when demand may overload the electricity supply infrastructure, increasing the risk of power failure. 

 

Energy Management Systems: 

Energy management is a strategy mainly utilized by businesses and managers of commercial buildings that leverage solutions to monitor, control, and optimize energy and ambiance. Energy management and control systems can reduce the energy use of systems in buildings and homes. 

By comparing data from these systems against weather data, building managers may be able to anticipate when changes in mechanical system design or operation are necessary. These systems also have the potential for allowing demand-side management and demand-response to interact with smart grids. Energy management can include start/stop functions, temperature setback/setup, and economizer controls.

In recent years, with the advancement of technology, we have seen an increase in the adoption of energy management solutions inside residential homes. These systems are also known as HEMS (Home Energy Management Systems) or SHEMS (Smart Home Energy Management Systems). The road to a fully equipped and connected smart home where occupants can monitor, control (or have auto control), and optimize the ambiance and energy utilization is still in its infancy. 

From smart connected thermostats and appliances to solar panels and energy storage solutions, an advanced HEMS can help occupants predict their home's energy consumption, better manage and control their costs and environmental impact, change how they interact with the local energy grid, and allow them to plan how to live more comfortably within their home.

Here is a good read from the National Renewable Energy Laboratory (NREL), which explains how an advanced HEMS solution would work. 

 

Energy/Environmental Modeling: 

This strategy is used to model changes in temperature and precipitation to better understand the effect of climate change on building systems. Advancements in climate models, building energy models, and other environmental modeling tools can help determine the size of building equipment for projected changes in temperature and precipitation levels. 

With a climate that is projected to become warmer, cooling design temperatures used in energy modeling should be raised. This will help to justify higher investments in cooling load avoidance measures. 

Energy and environmental modeling is a complex and highly technical subject, therefore, is mainly adopted in commercial and industrial buildings. However, if you are properly designing a new home or renovating your current one, as a minimum, it is good practice to hire a specialist to run an energy audit for your home. In such an audit, an expert can analyze and suggest passive solutions, insulation, and energy management solutions as well as run simple, or advanced, energy models to better plan, for example, your HVAC system. 

For further reading about energy modeling, you can tap into: About Building Energy Modeling

 

Final Thoughts

Extreme temperatures impact the comfort and well-being of household occupants, and in some cases may lead to illness and even death.

A home maintaining a temperature of 78°F during summer and 68°F during winter is considered comfortable and energy-efficient.

By investing in good insulation, air tightening, and efficient HVAC solutions that will make your house energy-efficient, you can achieve considerable financial savings as well as live in a truly sustainable home with easy breezy designs.

Key strategies covered in this blog:

• Building Envelope / Passive Strategies 
  • Foundation, Wall, and Roof Insulation (beyond code)
  • Stack and/or Cross Ventilation
  • Air and Water Barriers
  • Passive design (see our “passive house” blog for further details)
• Cool Roof 
• Design with Plants
• Energy Management Systems
• Energy/Environmental Modeling 

Be sure to check out more strategies to withstand heatwaves in our Black and White Beach House blog. 

KEEP COOL. BUILD RESILIENCE. EAMPACT.