A complete guide to green features for sustainable buildings
Updated: May 21
Thank you for your encouraging feedback on the Green Mark templates, it's been a great motivator for JOS to continue creating new articles. In response to several requests, I'm now sharing a list of common green features along with their design considerations. This article isn't meant to be a checklist, but rather a comprehensive guide to creating outstanding sustainable buildings.
Green building design is a versatile process with multiple strategies, from employing local eco-friendly construction materials to on-site renewable energy production. Green-friendly building design provides ample flexibility, enabling it to capitalize on the site's natural resources and the unique synergies of individual "green building technologies" for a more significant cumulative effect.
A more condensed list of green features was shared in the previous article.
A green building should consider the green features in the following categories:
Energy
If we were to draw an analogy between energy conservation in buildings and weight loss in humans, we might think about energy as the "fat" that a building needs to "shed". What, then, would be the most effective weight loss program for a building?
Just as the healthiest and most effective way for a person to lose weight involves reducing caloric intake, the most sustainable and efficient method for a building to "lose
weight" is to first reduce its energy consumption. Only after achieving this should energy efficient systems be implemented to make a greater impact. Innovative technologies, such as sensors and monitors, can be likened to supplements or special programs used in weight loss—they should be considered as enhancements, applied only after the building has effectively optimized its energy use through other strategies.
Air conditioning and heating system:
In most buildings, the largest energy consumers are the air conditioning and heating systems. Therefore, improving the efficiency of the air conditioning system (let's use the tropical climate as an example) is often at the top of any sustainable design checklist. In tropical climates like Singapore, buildings might aim for a chiller plant efficiency of 0.56 to 0.58 kW/RT. This efficiency is a result of the combined performance of the chiller, chilled water pump, condenser water pump, and cooling tower.
The project might also explore newer types of chillers, such as Magnetic bearing centrifugal chillers or absorption chillers. Absorption chillers are particularly suitable if the project generates waste heat and has a demand for hot water.
In situations where there are significant variations in load during the day and night across different buildings, a district cooling system could be a viable option. Thermal storage is effective when there is a substantial difference between peak and non-peak electricity costs, thereby balancing equipment load and operational costs.
Facade System
Check out the article about facade design.
The building facade acts as the boundary between the internal and external environments, shielding occupants from outside influences such as noise, pollution, and weather conditions. It's also a crucial element for sustainability, as it can significantly reduce the internal air conditioning load. The less heat is transferred from the outside to the inside, the less strain is placed on the cooling/heating system.
Additionally, the building facade can enhance daylight and natural ventilation. A well-designed shade can block direct sunlight, reducing glare, while also allowing sufficient daylight to illuminate the interior, minimizing the need for artificial lighting. A facade equipped with operable windows allows natural airflow to create a pleasant breeze, all while preventing rain from entering the building. Wind and rain simulations can be used to map and verify the design's effectiveness.
Generally, the facade should have a smaller window area, as heat tends to transfer more readily through glass than through walls. These factors are usually quantified through the U value, SC value, or K value of materials. In Singapore, the Envelope Thermal Transfer Value (ETTV) is commonly used to measure the facade's heat transfer.
And indeed, glass is a beautiful and versatile material that enhances architectural designs with its transparency, reflection, and the ability to support various creative expressions. While heat transfer is a consideration, it should not limit architectural creativity. To strike a balance between aesthetics and functionality, projects may consider building-integrated photovoltaics (BIPV), low-emissivity (low-e) glass, insulated glass, or spandrel glass. However, it's important to keep in mind that glass is a high-cost item in building construction, and its use can significantly impact the overall budget.
Sensor System
Sensor systems are often viewed as "supplements" for buildings, aimed at reducing energy consumption. They tend to perform best in buildings that are already optimized for minimal energy use.
Common sensor systems include:
Daylight sensors: These are typically placed around the building perimeter to reduce the use of artificial lighting.
Motion sensors: These are used in less frequently occupied areas (such as toilets, staircases, corridors, lobbies, storerooms, etc.) to optimize the usage of air conditioning, ventilation fans, or lighting.
CO2 sensors: These balance the intake of outdoor air and human occupancy in air conditioning systems, thus minimizing energy consumption.
Infrared sensors: These are effective occupancy sensors that can precisely detect human presence without physical movement, especially useful in office areas.
CO sensors: These can reduce the energy consumption of ventilation fans in parking areas during periods of low demand.
Rain sensors: These can minimize automatic landscape watering, leading to a reduction in both utility and energy usage.
Temperature sensors: These sensors monitor the ambient temperature in a building and can adjust HVAC systems accordingly to maintain a comfortable environment while optimizing energy use.
Humidity sensors: These sensors can monitor and control the moisture levels in the air, which is crucial in certain environments like laboratories, server rooms, or museums. They can also help to maintain comfort in residential and office buildings.
Light level sensors: Also known as photometric or lux sensors, these measure the intensity of light. They can be used to control lighting systems, dimming or turning off lights when there's enough natural light, or increasing lighting when needed.
Water leakage sensors: These sensors can detect leaks in a building's plumbing system, helping to prevent water damage and waste.
Air quality sensors: These sensors monitor levels of pollutants or particles in the air, which can be crucial for maintaining a healthy indoor environment.
Smoke and carbon monoxide detectors: These sensors are crucial for safety, detecting the presence of smoke or carbon monoxide in the building.
Smart meters: While not strictly sensors, these devices can provide real-time data on energy and water usage, helping building managers to track and optimize resource use.
Renewable Energy
Renewable energy, often referred to as "clean energy," leverages naturally replenishing resources or continuous processes in the environment. It's a favourable option as it harnesses "free energy" from nature, despite the fact that the production process for renewable energy harvesting equipment may have environmental impacts.
Typical types of renewable energy include the following, with the selection depending largely on the specific site of the project:
Solar Energy: Photovoltaic panels transform sunlight into electricity using silicon.
Wind Energy: Wind turbines situated in areas with high wind speeds generate power as the natural wind speed turns the blades, which drive an electricity generator.
Hydroelectric Energy: When water falls due to gravity or moves at high speed, it turns the blades of a hydroelectric generator, producing energy.
Projects situated in areas rich in natural resources might also consider geothermal energy, tidal wave energy, or biomass energy.
Other Systems
There's a wealth of innovative designs available that can significantly lower energy consumption. Many of us are already familiar with technologies such as LED lighting, light tubes that direct sunlight to areas deep within a building, variable voltage variable frequency (VVVF) lifts with sleep modes, heat recovery systems, variable speed drive (VSD) pumps, variable air volume (VAV) fans, and hybrid air conditioning systems that use ceiling fans. Each unit of energy saved contributes to the overall energy reduction goal of the building. Therefore, it's crucial to identify and leverage every potential opportunity for energy savings.
Material
The cost of building materials typically accounts for 45% of the total construction cost of a building, as per LEED guidelines. This makes building materials the single most expensive category in a construction project. These materials encompass everything from the building structure to interior finishes and external landscaping.
The general principle for sustainable use of building materials is the "reduce, reuse, and recycle" approach. This means minimizing the use of new materials, repurposing existing materials wherever possible, and recycling materials at the end of their lifecycle.
Construction materials
There are many materials better than concrete. There exist numerous alternatives to traditional concrete that are more environmentally friendly. A key aspect of sustainable building design is the ability to reuse building materials, opt for products that are recycled or can be recycled, manage construction waste effectively, and choose materials that contribute to a healthier indoor environment.
One such sustainable option is low-carbon concrete, which is produced using a carbon-negative manufacturing process. This approach addresses serious environmental concerns and significantly reduces the carbon footprint associated with the production of concrete. Moreover, the efficient use of concrete – reducing the quantity used per unit of floor area, as measured by the Concrete Usage Index (CUI) – is highly encouraged in green building projects.
Additionally, projects should aim to minimize the amount of waste generated during construction and strive to recycle construction waste materials. This will help reduce the amount of waste that ends up in landfill or incineration facilities. Materials that are typically sent to recycling companies include concrete, wood, masonry, cardboard, steel, aluminum, furniture, tiles, and landscaping debris, among others. These materials can then be repurposed and reintroduced into the construction process, further enhancing the sustainability of the project.
Building materials/products:
Recently, green rating systems have begun to focus more on comprehensive sustainability rating systems rather than individual types of green materials. This holistic approach encourages market integration and a broader view of sustainability in building projects.
It's essential for a building project to scrutinize the sourcing of raw materials for products, the ingredients used, and their impact throughout the product's life cycle.
To aid in the assessment of sustainability efforts invested in material sourcing, manufacturing, and delivery, we often refer to the following certifications for materials/products:
Cradle to Cradle certified: It covers a wide range of products, from building material to baby products. The certification verifies its environmental impact via critical sustainability aspects.
FSC Certified, COC Certification: This is for wood related products that exhibits responsibilities and efforts to protect forests and the environment.
Energy Star: it certifies electronic appliances on their energy efficiency. This is organised by US Environmental Protection Agency.
Green Seal: it's a 3rd party ISO type 1 certification, a founding member of the Global Ecolabelling network. It follows EPA's requirements for its product and material certification.
Singapore Green Building product: Managed by Singapore Green Building Council, the Green Building products are certified according to the environmental impact of the product from the sourcing, manufacturing process, to the health and environmental impact of the product.
Singapore Green labelling scheme: administrated by Singapore Environment Council, the certification covers a wide range of products.
It is important to know that sustainable buildings should be designed to last, and it's important to consider the durable and sustainable material/product.
Indoor Air quality (IAQ) and Thermal Comfort
The majority of our time, approximately 90%, is spent indoors. As such, the quality of indoor air plays a significant role in influencing our health, productivity, and even our mental development over time. The issue of indoor air quality is intimately connected to the phenomenon known as Sick Building Syndrome (SBS).
Green building standards place significant importance on maintaining indoor air quality. This is achieved through guidelines that dictate the properties of conditioned supply air, the elimination of indoor and outdoor pollutants, and regular maintenance schedules.
1. Air conditioning and ventilation:
Numerous studies have highlighted the strong correlation between ventilation and indoor air quality (IAQ). The significance of IAQ has grown particularly in light of events like SARS, Covid, and local climate pollution incidents. Broadly, high-quality indoor air is characterized by low CO2 concentration and minimal harmful chemical emissions from indoor materials. During hazy seasons, good IAQ also implies minimal intrusion of outdoor pollution.
CO2 concentration is a key indicator of IAQ. In urban spaces, outdoor air has a CO2 concentration of around 400ppm, whereas the indoor concentration should be kept under 1000ppm. Higher concentrations can lead to drowsiness, headaches, or decreased productivity. To maintain low CO2 levels, fresh outdoor air is introduced into the building. However, as this air requires conditioning, there can be a trade-off between IAQ and energy consumption. CO2 sensors are often used to strike this balance.
2. Indoor and outdoor pollutants:
Indoor pollutants include emissions from building materials, cleaning products, paints, and combustion sources like tobacco, heating, and cooling appliances. Common concerns include volatile organic compounds (VOCs) in paints, insecticides, cleaning products, urea-formaldehyde in pressed wood products, and mold growth in damp, poorly ventilated areas.
High-efficiency filters, such as MERV 14 filters, are crucial to prevent outdoor pollutants from infiltrating the building. Considering these filters can cause pressure drop in the ventilation system, they might be manually inserted only during pollution events, while fan sizing should accommodate these high-grade filters.
3. Maintenance:
Maintaining high IAQ requires ongoing efforts. Occupancy surveys can be useful to gather feedback on IAQ and thermal comfort. Regular "flush-outs" (delivering a high volume of outdoor air into the space) can help remove accumulated CO2 and bacteria.
4. Thermal comfort:
Air conditioning was perhaps one of the significant inventions of history.
- Lee Kuan Yew, Singapore's founding father.
Air conditioning has dramatically improved our comfort in indoor spaces, especially during the hot summer months or in tropical climates. Comfort is subjective and depends on a range of factors. Research identifies six primary factors affecting thermal comfort, divided into environmental and personal categories: air temperature, air speed, relative humidity, mean radiant temperature, clothing insulation, and metabolic rate.
The industry-standard Predicted Mean Vote (PMV) model, developed by Fanger and standardized in EN ISO 7730, is often used to guide thermal comfort conditions. The PMV model uses a scale from -3 (very cold) to 3 (very hot), with a range of -0.5 to 0.5 considered "comfortable". Despite criticisms suggesting regional or gender-based variations in thermal comfort, most projects still adhere to the ASHRAE 55 PMV model as a general design guideline.
Water
A green building should strive to reduce water consumption and optimize the use of recycled water for non-potable purposes.
Here are some common strategies for conserving water:
1. Install Low Flow Water Fittings: This reduces the volume of water used in faucets, showers, and toilets, thereby saving a significant amount of water over time.
2. Rainwater Harvesting: If feasible, collect rainwater and utilize it for purposes like irrigation, toilet flushing, or general cleaning.
3. Greywater Recycling: Reuse greywater – that is, gently used water from sinks, showers, and washing machines – for toilet flushing, irrigation, or general cleaning.
4. Utilize Recycled Municipal Water: If available, use city-level recycled water sources like Newater in Singapore.
5. Landscape with Local or Low-Water Plants: Choose plant species native to your area or those that require less water to thrive. This not only conserves water but also supports local biodiversity.
6. Install Water Sensors: These can help detect and prevent water leaks, thereby avoiding unnecessary water wastage.
7. Optimize Water Use in Cooling Towers: If your project involves a cooling tower, maximize the cycles of water usage. Aim for a minimum of 7 cycles of concentration with an effective filtration system to meet water quality requirements.
8. Collect Condensate Water from Air Handling Units: This is a viable source of recycled water, especially in humid climates.
9. Benchmarking: Set water consumption targets and measure your usage against them to raise awareness and motivate ongoing water-saving efforts.
By implementing these strategies, a building can significantly reduce its water footprint and contribute to overall environmental sustainability.
Design and Innovation
Embracing sustainable design is an invigorating journey of growth and transformation. It's about shaping ideas with longevity in mind, crafting spaces that uplift their inhabitants, and forging platforms for continual learning. Sustainable design is a commitment to contributing positively to the enduring narrative of global sustainability.
Sustainability isn't an afterthought—it's a fundamental strand in the DNA of design, a resonant chord strummed in the symphony of creation. It's a collaborative dance, weaving together the unique perspectives and expertise of architects, engineers, project managers, contractors, facility managers, building owners, and future users. Each project, a unique tapestry, weaves its own tale of sustainability.
A green building doesn't merely exist in harmony with the environment—it actively contributes to its wellbeing. It harnesses the bounty of nature's gifts for the benefit of our planet and its people. We, as privileged inhabitants of this Earth, benefit daily from its resources. Thus, it is our shared responsibility to nourish and preserve the environment that sustains us.
Sustainability is a calling that needs no special invitation or permission. It's a way of life, a mindset that shapes our daily actions and decisions. It's about embracing the simple, yet profound joy that comes from living sustainably.
So, here's a toast to the exhilarating journey of sustainability! Let's celebrate the joy and fulfilment that comes from creating a world that flourishes in harmony with nature.
Reference:
1. US Green Building Council, USGBC.og.
2. LEED rating system.
3. IS GREEN CEMENT THE FUTURE OF SUSTAINABLE CONSTRUCTION?, kapre.
4. Green cement a step closer to being a game-changer for construction emissions, The conversation.
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6. Elemental green, https://elemental.green/23-green-certifications-to-look-for-building-remodeling-home
7. Whole building design guide: https://www.wbdg.org/resources/green-building-standards-and-certification-systems
8. EPA Indoor Air Quality Report: https://www.epa.gov/report-environment/indoor-air-quality#:~:text=The%20potential%20impact%20of%20indoor,higher%20than%20typical%20outdoor%20concentrations.
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12. ANSI/ASHRAE Standard 55-2017, Thermal Environmental Conditions for Human Occupancy.
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