The Importance of Energy Efficient Walls

qeatechmarkstg on August 15, 2023

Undoubtedly, walls are an essential part of a building’s infrastructure. They act as a barrier between the indoor and outdoor environments, providing insulation to minimize heat transfer. Insulating walls effectively reduces the heat flow into or out of the building, helping to maintain desired indoor temperatures and reducing the reliance on heating and cooling systems. Well-insulated walls can significantly reduce energy consumption and associated costs.

There are a variety of ways to achieve greater energy efficiency within the walls of a building. Some of these strategies include:

Insulation

Adding insulation to walls is one of the most effective ways to improve energy efficiency. Different insulation materials, such as fiberglass, cellulose, foam boards, or spray foam, can be installed within the wall cavities. Determining the most energy-efficient insulation type depends on the specific project requirements. Insulation’s thermal resistance, commonly referred to as the R-value, is an important factor to consider. The higher the R-value, the better the insulation’s ability to resist heat transfer.

Air Sealing

Proper air sealing of walls helps prevent air leakage, which can lead to energy loss and discomfort. Seal gaps, cracks, and penetrations in the walls with caulking or weather-stripping to minimize air infiltration and improve energy efficiency.

Exterior Insulation

Adding insulation to the exterior of walls, commonly known as exterior insulation and finish systems (EIFS), can greatly enhance energy efficiency. Exterior insulation minimizes thermal bridging and provides a continuous thermal barrier, improving insulation performance and reducing heat loss/gain through the walls.

Thermal Mass

Incorporating materials with high thermal mass, such as concrete or masonry, into the walls can help regulate temperature fluctuations. Thermal mass absorbs and stores heat, releasing it slowly to help maintain more stable indoor temperatures, reducing the need for additional heating or cooling.

Reflective Coatings

Applying reflective coatings or light-colored paint on exterior walls can help reflect solar radiation, reducing heat absorption and keeping the building cooler during hot seasons. This can help reduce cooling loads and energy consumption.

Advanced Framing Techniques

Optimize wall framing to reduce thermal bridging and increase the space available for insulation. Techniques such as insulated headers, advanced stud spacing, and ladder blocking minimize heat transfer through the framing components.

Building Envelope Integrity

Ensure that the wall system is well-maintained and free from damage or deterioration. Regular inspections and repairs of the building envelope, which include walls, help prevent air leakage, moisture infiltration, and energy loss.

It is important to consider building codes, climate conditions, and the specific requirements of each project when implementing these strategies. Working with energy professionals such as QEA Tech can help identify where the most significant energy loss from a building’s walls is occurring and determine the retrofit methods that maximize energy savings and ROI.

Unlocking building energy savings through the building envelope

qeatechmarkstg on July 20, 2023

The building envelope refers to the outer shell or skin of a building, separating the interior and exterior environments. It serves as a barrier against heat, cold, moisture, noise, and air infiltration. The components of the building envelope, such as insulation materials, windows, and doors, determine the energy efficiency and overall performance of the structure.

Several studies identified saving potentials from the building envelope in European countries in the range between 75% and 80% (Hummel et al, 2021). Of the annual air conditioning heating energy consumption of public buildings, there was about 50% consumed by the heat transfer of the building envelope (Feng et al, 2016). Studies have also shown thermal insulation can reduce buildings’ energy consumption up to forty percent (Abdelhafiz et al, 2022). Below are some critical aspects of the building envelope.

Thermal Insulation: Preserving Comfort, Reducing Energy Demand

Insulation materials, like fiberglass, cellulose, or foam, act as barriers to heat transfer, preventing unwanted heat gain in summers and heat loss during winters. By minimizing the need for heating and cooling, effective insulation significantly reduces energy consumption, leading to substantial cost savings for building owners and occupants.

Air Sealing: Guarding Against Energy Loss

Air leakage through cracks, gaps, and poorly sealed joints can lead to significant energy loss. Airtightness is a crucial aspect of the building envelope, as it prevents uncontrolled air movement, enhancing the effectiveness of insulation and reducing the load on HVAC systems. By minimizing air infiltration, buildings can maintain more stable indoor temperatures, reduce the workload on mechanical systems, and save energy.

Windows and Glazing: Harnessing Natural Light and Passive Heating

Windows, an integral part of the building envelope, provide natural light, ventilation, and a connection to the outside world. However, they can also be a significant source of heat gain or loss. Energy-efficient windows with low-emissivity coatings, multiple panes, and insulating gas can greatly reduce heat transfer, enhancing both comfort and energy savings.

Solar Reflectance and Thermal Mass: Controlling Heat Gain

The building envelope’s design can incorporate materials with high solar reflectance to minimize the absorption of solar radiation, reducing the cooling load on the building. Additionally, thermal mass materials, like concrete or stone, absorb and store heat during the day and release it slowly at night, aiding in maintaining stable indoor temperatures and reducing the reliance on mechanical cooling systems.

Moisture Control: Mitigating Energy Loss and Building Damage

Moisture infiltration can degrade insulation, promote mold growth, and compromise the structural integrity of the envelope. Effective moisture management through vapor barriers, weather-resistant coatings, and proper drainage systems ensures that the building envelope remains dry, reducing the risk of energy loss and potential long-term damage.

Overall, the building envelope is a critical line of defense against energy loss and environmental elements, making it an essential aspect of any sustainable building design. By focusing on the design, materials, and construction techniques of the building envelope, we can unlock significant energy savings, reduce carbon emissions, and enhance occupant comfort. Investing in energy-efficient insulation, high-performance windows, air sealing, solar reflectance, and moisture control measures can lead to substantial long-term benefits for both the environment and building.

Building Envelope Retrofits: Revitalizing Existing Buildings

qeatechmarkstg on January 26, 2022

The building envelope is the part of a building that separates the outside climate from the interior, providing shelter and performing as a protective membrane over the main structure. The building envelope has an important obligation; it helps keep occupants dry, warm, or cool, can help in controlling noise and odors from the exterior, provides safety and security, and it is essential for maintaining suitable indoor air quality. It needs to perform all the aforementioned roles while also creating curb appeal and maintaining an aesthetically pleasing appearance.

What does the Building Envelope Include?

The building envelope components include the materials that comprise the foundation, wall assembly, roofing systems, glazing, doors, and any other penetration separating the interior and exterior. The connections and compatibility between these elements are also a critical part of ensuring that the building envelope functions as intended. An envelope must properly maintain control of the heat flow, moisture flow, and airflow while providing structural integrity and shelter from the rain, snow, hail, wind, dust, pollutants, allergens, and pests. A system’s ability to achieve these tasks is what classifies a high-performance and low-performance building envelope.

Impacts of Building Envelope Deficiencies

Any deficiencies in the envelope system’s performance may impact the overall building performance and subsequently the energy usage/carbon footprint of the building. Unsatisfactory insulation levels will compromise the ability to regulate heat flow, which will reduce occupant comfort and will cause the HVAC system to work harder. Gaps, cracks, and holes in the envelope will result in uncontrolled air leakage which will cause the conditioned air to escape through the roof and walls, creating an unwanted extra load on the HVAC system. Undesirable temperatures and humidity levels may occur and moisture vapor transfer through the envelope will result in moisture-related damage and premature deterioration of building materials. A leaky roof, defective rain screen, or failed window frame can let water enter the building, sometimes in substantial quantities which may cause structural damage, mold, mildew, or other threats to indoor air quality and occupant health.

Retrofitting the Building Envelope

Retrofitting or restoring building performance for an existing commercial building envelope might entail adding insulation, sealing air leakage paths, replacing windows, installing a new roofing system, or any combination of these tactics which will be discussed further. There are many high-performance products available to choose from, all enhanced by chemistry and new technological advancements.

Prior to commencing any sort of retrofit strategies, it is first important to identify the existing problems in a building envelope, either commercial or residential. A popular and non-invasive method that has recently commercialized the market is Infrared Building Envelope Inspections. These are fast, accessible, and efficient means of examining building envelope efficiency using an infrared camera that detects anomalies through temperature fluctuations. These assessments are typically performed on the exterior of the building at sufficient interior and exterior conditions. With an adequate temperature difference between the interior and exterior of the building at the time of assessment, undesirable energy losses through the envelope can be identified. This strategy can help determine whether targeted retrofits or full deep energy retrofits will be required to upgrade the building under investigation. Once these inspections have been performed and breakdowns of retrofit strategies have been reviewed by the building-owner, the rehabilitation project can begin.

Targeted vs Deep Energy Retrofits

There are several types of deep energy retrofit options available for a building, however, focusing on the building envelope, there is typically an option to choose between a deep energy building envelope retrofit, a targeted retrofit or a hybrid option. After identifying the components and points of weakness in the envelope, a cost analysis is performed to access the lifespan, rehabilitation project cost and potential future energy savings against different repair options. A targeted rehabilitation approach is the cheaper option that focuses on repairing specific areas of weakness that were determined during the assessment stage. This approach typically requires continuous upgrades and component reviews throughout the lifespans of the building. Replacing or repairing individual windows, fixing sealant joints and replacing specific damaged roofing areas are some examples of targeted rehabilitation strategies.

A deep energy retrofit on the other hand, consists of an extensive whole-building analysis and construction process aimed at reducing a building’s energy use by at least 50% compared to a historical baseline and usually includes envelope upgrades as part of the retrofit. Focusing on the envelope, a deep energy retrofit usually consists of a full replacement of the building envelop components minus the structure of the building. A deep energy retrofit of the building envelope focuses on redesigning the system to increase its performance which will in turn reduce energy usage bills in the building and increase the lifespan of the construction. The main approaches when dealing with a full-scale envelope replacement is to address the following items: Insulation and thermal bridging, Air tightness and infiltration, glazing and solar shading. These are the main aspects of an envelope that will determine how energy within in a building is being stored and controlled.

The design stage for the retrofit is a complex and important part of the process. While maintaining the existing structure of the building the envelope members must be redesigned accordingly taking into consideration the thermal and hygrothermal performance, air and water control, sound control and aesthetic appeal. The connection and detailing of the new joints must be carefully designed in order to have effective and long-lasting control of external factors. This building envelope redesign process is similar to a new build design, however there are existing factors that must be taken into consideration. The building tenants and their comfort during construction must also be considered. While this process is expensive and timely, there have been many case studies in Canada and other cold climates that show successful deep energy building envelope retrofits.

It is important to remember that while the envelope plays a crucial role in the energy efficiency of the building, it is the entire building function that needs to be considered together as a living unit. Other aspects including HVAC function in accordance with the envelope and should also be evaluated during a deep energy retrofit project. The envelope, however, has been shown over the years to be one of the leading areas of concern and is crucial to investigate when looking at improving energy efficiency of a building and pushing for a more sustainable future.

The Case for Building Reuse and Retrofitting

Affordable housing is another challenge that has affected major cities like Toronto, Vancouver, and New York. The time it takes for a new house development to get from approval to market is too long which is a challenge for the increasing demand of affordable housing. One method of helping speed up the procedure is to direct focus towards restoring, retrofitting and or reusing existing buildings as discussed in this reading. Upgrading, maintaining, or reusing an existing building structure for a rehabilitated use is normally less expensive than demolishing and constructing a new building. These approaches are far better for the environment and leave a smaller carbon footprint if executed properly. Many in the industry are also calling for governments to invest in green retrofits as part of post-COVID stimulus funding. There has also been a call on governments to provide financial assistance to not-for-profit, multi-residential buildings, and calls for retrofits for affordable housing strategies.

Accelerating deep energy retrofits will depend on financial incentives at both the national and local level. Establishing renovation programs for owners, property investors, and occupants to recover some or all of the costs of the project will speed up the adoption and maximise the savings available over the medium- and long-term. Multiple countries and cities are already following this approach. In Canada, The Trudeau government has committed $2B to large-scale building retrofits that drive energy efficiency and sustainable communities. In order to meet Canada’s 2030 GHG emissions reduction it is crucial that the energy usage of building stock be addressed. It is the existing buildings that are in need of attention.

Looking for a quick envelope assessment? Perform a quick and easy non-intrusive Infrared envelope assessment to get an idea of how well energy is being stored and controlled in your building. This is the first and easy step towards a greener and brighter future.

About the author

David Gertsvolf

David has dedicated his career to the Building Science Industry. He holds two Architectural Diploma’s, a Bachelor’s degree in Building science, and is currently studying in the Master’s of Applied Science in Building Science Program at Ryerson University. Through his research, studies, and industry experience David seeks to drive the field of construction to a greener and brighter future. David is a passionate and hard working individual who is excited to thrive as an industry professional and contribute to a growth in sustainable construction.