Energy efficiency in green buildings to reduce energy waste

11 Mar

what is energy efficient architecture? Read on to discover these green building approaches examples

Energy consumption in green buildings and energy solutions to reduce energy consumption

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Improve energy performance for a more sustainable future

Buildings and the real estate industry in general contribute around 30% of total global energy consumption, making them a vital consideration in the push for a green energy transition away from fossil fuel dependency.

Energy efficient buildings are, like electric and eventually hydrogen-powered cars, a necessary step for the future of our planet, not least due to the ongoing process of urbanization which will see an estimated 70% of the world’s population living in cities by 2050 (Bratman).

Green buildings new construction

Key factors to consider in building energy efficiency include building orientation and its footprint but there we step into the realm of site planning and selection, architecture and engineering. Beyond new construction then, how can we as green building consultants help in the refurbishment of our existing buildings - a fundamentally more energy efficient and sustainable approach?

Green buildings refurbishment

Overarching strategies in a refurb project include reducing energy demand, increasing source efficiency, and tracking the live energy use of the building. Together these provide the building blocks of energy efficient refurbished buildings. The ideal goal of course being net zero or net positive buildings.

Specifically, demand can be reduced through strategies such as passive design and green roofs. Energy source efficiency can involve implementing energy efficient lighting, efficient HVAC (air con ventilation) and elevator systems, as well as renewable energy production on site via solar panels on the roof, for example.

energy efficient building solutions

With the incorporation of some or all of these energy reducing green building strategies, there is then a requirement for ongoing tracking and monitoring of progress in energy efficiency so that facilities management have a real time picture of the energy consumption patterns in the building.

Demand Reduction in green buildings

Demand reduction in sustainable green buildings involves strategies that reduce the upfront energy needs, lowering the amount of energy consumed and paving the way towards greater energy efficiency overall. Passive design as well as the implementation of green and cool roofs are several strategies to reduce energy demand.

Passive Design in sustainable buildings - energy saving in construction

Passive design is a concept in which the sustainable building design works with local climate conditions to reduce the need for energy use. Passive design includes strategies such as daylighting, natural ventilation, and passive heating, which all can reduce energy demand. This is all done in the building modeling phase of a new construction project.

The use of daylighting through windows, skylights and other openings can reduce the need for electrical lights. In addition, in hotter months, the use of daylighting can reduce cooling loads, as on average it produces less heat per unit of illumination than electric lights.

Natural ventilation utilizes outdoor air and winds to bring fresh air into a building. This can help regulate indoor air quality and appease the need for mechanical ventilation, as well as increasing thermal comfort through passive cooling. Most commonly, natural ventilation can be incorporated through the installation of operable windows. This strategy is dependent on the quality of the outdoor air available in the site in question, a factor that can vary by hour, day and season.

energy efficient buildings examples

In addition, solar energy can be used to reduce the need of heating, for example, direct solar gain - which provides places where the sun can enter a space directly - can help to heat a living area.

If paired with thermal mass structures, the sun can heat a mass such as a wall throughout the day and release this heat throughout the evening - a common strategy in traditional buildings in the Middle-East for example.

Green Roofs & Cool Roofs in Sustainable Buildings

Roofs are often an untapped resource in buildings, when in reality they have a lot of potential for energy demand reduction. Roofs are subject to the highest amount of solar irradiance across the entire building envelope (Costanzo).

Cool roofs utilize highly reflective coating such as white paint to increase reflectivity, while green roofs use vegetation as a cover to increase cooling capabilities of a building (Costanzo).

Although there are pros and cons to green roofs and cool roofs, both reduce building cooling demand (Costanzo). Cool roofs have been found to lower the temperatures of roofs more than green roofs, but green roofs provide some insulation in cooler seasons.

Green roofs provide additional benefits such as air purification and biophilia benefits if made accessible to building occupants. However, due to the maintenance factor of greenery, cool roofs are an easier practice to implement in terms of initial investment.

Energy Efficiency Lighting in Sustainable Buildings

A low hanging fruit of energy efficiency is to incorporate energy efficient lights such as LED bulbs. Generally, this is a very cheap intervention that can provide considerable energy savings.

Such bulbs consume more than three times less than the energy used by fluorescents and less than a seventh of the energy used by incandescent bulbs. In addition, LEDs provide a higher lumen output, which increases safety and sight, they also have a much longer life span (Taddonio)

In addition to lighting replacements, other strategies such as motion sensors, dimmers and timers can be used to reduce energy and maintenance costs. Hallway lighting can be adjusted based on the time of day and natural light presence.

Desk and office lighting can be adjusted based on hours worked in office and dimmed or turned off when not necessary (“Managing”). These strategies can be very effective at reducing energy consumption, especially when combined.

Efficient Machinery

Once demand reduction strategies have been implemented, the next step is to make sure that the appliances and machinery that are functioning within the building are as efficient as possible and are consuming less energy. For example, the HVAC systems, elevators, and other machinery within the building.

HVAC systems generally run on a clock depending on the building use type. For example, an apartment building may need to be run on a 24-hour cycle, while an office building HVAC system can be shut off at night when no one is in the workplace to avoid excess energy use.

energy efficiency solutions

In addition, the systems themselves should be chosen based on those that are designed to consume less energy when in use. Various space types align better with different HVAC systems, so proper planning is required to make the most informed decisions.

In addition to HVAC systems, other machinery such as elevators tend to be large energy consumers in buildings. It is important to install energy efficient lifts and elevators to avoid excess energy use.

To aid with the decision-making process, there are various standards and resources. For example, the U.S. Environmental Protection Agency’s Energy Star Program designates energy-efficient appliances that contain more high performing systems (“The Science”).

Renewable Energy Production in Green Buildings

In addition to incorporating energy efficient appliances and fixtures, the use of renewable energy and the potential to produce it onsite is a very effective green building strategy. Solar is the most common and easily applied renewable energy source on a building site.

Panels are commonly placed on roofs and should be angled to best receive the sun, which varies depending on location and building orientation. However, newer technologies are providing ways that solar technology can be incorporated into facades, for example.

When making sustainable solar energy decisions, it is important to consider location and feasibility of potential solar gain, as well as if there is enough area to install enough panels to provide an ample energy source - at the very least, a green building project team should consider wiring in the cables for future installation of solar panels on the roof during the refurb or construction process, even if funds are not immediately available to purchase them.

Benchmarking, Tracking and Monitoring green building energy

Once a green building energy efficiency plan has been implemented, there is a need for building energy use monitors to track ongoing performance. Several third-party organizations such as ASHRAE, ANSI, and IESNA provide baselines; for example, ASHRAE 90.1-2010 is the energy efficiency standard.

After a baseline is set and goals are made, a process known as commissioning is implemented. This process, as described in the LEED green building standard is the “process of verifying and documenting that a building/all of its systems are planned, designed, operated and maintained to meet the owners project requirements” (LEED).

This concept encourages projects to continue to operate according to the initial goals and monitor energy consumption to maintain desired efficiency levels.

The installation of sub-meters and automated building controls allow building operation managers to track energy costs and usage by area, as well as aiding the control of building wide energy use.

Building Energy Management Systems (BEMS) are common systems that are used for monitoring and controlling building energy use.

Net + Energy in Green Buildings as a way to go beyond merely saving energy

The ultimate goal for us as sustainability consultants in real estate is to create Net Positive Energy buildings, meaning that more energy is created on site from renewable sources than is consumed by the building—therefore giving back rather than taking from energy sources.

In other words, going further than efforts to merely save energy or improve energy efficiency and reduce energy consumption in residential buildings, for example. Here we look to go much further than that.

Net Zero Energy buildings, a relatively more attainable yet nonetheless challenging goal, produce the same amount of energy on site as they consume, avoiding energy resource depletion with energy efficient equipment and so on.

To achieve that requires systems thinking, looking at a building in a joined-up manner, exploring how distinct elements of the system can work together to make a more efficient whole.

Sustainable Building, energy conservation and carbon emissions Sources used in this article

Bratman, Gregory, and Gretchen Daily. The Benefits of Nature Experience: Improved Affect and Cognition. Tech. Vol. 138. Stanford: n.p., 2015. Landscape and Urban Planning. Stanford University Libraries. Web. 24 Oct. 2016.

“Building Energy Management Systems Bems.” Building Energy Management Systems BEMS - Designing Buildings, 27 Oct. 2021, https://www.designingbuildings.co.uk/wiki/Building_energy_management_systems_BEMS.

Costanzo, V., et al. “Energy Savings in Buildings or UHI Mitigation? Comparison between Green Roofs and Cool Roofs.” Energy and Buildings, Elsevier, 12 May 2015, www.sciencedirect.com/science/article/pii/S0378778815003527.

“Managing Energy Costs in Hospitals.” 2010.

O’Malley, Christopher, et al. “Urban Heat Island (UHI) Mitigating Strategies: A Case- Based Comparative Analysis.” Sustainable Cities and Society, Elsevier, 14 June 2015, www.sciencedirect.com/science/article/pii/S2210670715000657.

Taddonio, Kristen. “Energy-Efficient Hospital Lighting Strategies Pay Off Quickly.” BUILDING TECHNOLOGIES PROGRAM, July 2011, commercialbuildings.energy.gov/hospital.

“THE SCIENCE BEHIND HEALTHY HOMES: 25 FACTORS THAT IMPACT YOUR HOME.” Delos, 2020.

Further Reading

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Matt Morley