Updated: Apr 25, 2021
Thanks for the great positive feedbacks on the #greenmark #templates which motivates JOS to continue publishing new articles. In response to several requests, I'm sharing the common listed Green features and its design considerations. This article is not intended to serve as a checklist, but rather a comprehensive reference to a great sustainable building.
There are many different approaches to designing green buildings, from the labelling of local environmentally friendly building materials, to producing renewable energy locally. There is a great flexibility in the building design that is environmentally friendly, with respect to the site natural resources and the individual "green building technology" working together to achieve greater cumulative effect.
A shorter list of green features were available in the previous article.
A green building should consider the green features in the following categories:
If we consider energy as the "fat" of the building and encourage building to "lose weight", let's think about what is the most effective weight loss program?
To lose weight, the most healthy and effective way is to eat less. In addition, doing exercise and maybe some fat burning supplements or programs can be used as the booster.
Similarly, for building to "lose weight", the most sustainable and efficient way is to reduce the energy consumption first. Thereafter, the use of energy efficient systems can be more impactful. The use of innovative technologies like sensors and monitors should only be considered as the enhancement after project has implemented good energy optimisation strategies.
Air conditioning and heating system:
The biggest #energy guzzler is the air conditioning system and heating system in most of the buildings. Hence, air conditioning system efficiency (use tropical climate as an example) is always on the top of the sustainability design checklist. A building in the tropical climate like Singapore may target chiller plant efficiency of 0.56 to 0.58 kW/RT. This efficiency is contributed by the chiller, chilled water pump, condenser water pump, and cooling tower.
The project may consider new types of chillers like Magnetic bearing centrifugal chillers, absorption chillers (when the project has waste heat, and has hot water demand).
A district cooling system may be considered if there is significant load variations during the day and night in different buildings. Thermal storage works when the peak and non-peak electricity cost are significantly different, balancing the equipment load and running cost.
Building facade separates the internal and external environment and protects occupants from the external influences like noise, pollution and weather. Building Facade is also a key sustainable feature to reduce the internal air conditioning load. The less the heat transfer from external to internal, the less "work" will be imposed to the cooling/heating system.
In addition, building facade is also a good medium to enhance the daylight and natural ventilation. A facade with good shade may block direct sunlight, hence reduce glare. An optimised shading design also allows sufficient daylight to bounce into the internal space, hence reduce the need for artificial lighting. A facade with operable window allows natural wind to create comfortable breeze, while blocking the rain splashing into the internal space. Wind simulation and wind driven rain simulation shall help to map and verify the design effect.
In general, the facade should have less window area as more heat will transfer through glass compared with wall. All these are measured by material U value, SC value, or K value. In Singapore, ETTV is the general calculation to measure the facade heat transfer.
And yes, as we know, glass is such a great creation to elevate architectural designs, it creates the transparency and reflection, the smooth and flexible surface support any imagination. Heat transfer is one of the consideration but shouldn't restrict the creation of Architectural design. To balance the perspective and the functionality, project may consider building integrated photovoltaic (BIPV), low-e glass, insulated glass or spandrel glass. Usually the key consideration is the cost impact to the building as glass is a high cost item in building.
*Note: in order to reduce heat, facade shading or low-e coating must be applied at the outside surface of the facade, preventing heat transfer. For internal shading, it's meant to enhance the daylight or reduce glare.
Sensor systems are considered as "supplements" for buildings to reduce energy. And it works better with an optimised building which already consumes minimum energy.
The common sensor systems are:
- Daylight sensors at building parameters to reduce the lighting usage
- Motion sensors for less occupied area (toilet, staircase, corridor, lobby, store room, etc.) to optimise air con, ventilation fan or lighting usage
- CO2 sensors to optimise and balance the air con outdoor air intake and human occupancy, hence minimise the air conditioning system energy consumption
- Infrared sensor is an effective occupancy sensor to precisely detect human present without physical movement (especially in office area)
- CO sensor to reduce air park ventilation fan energy consumption when there is low demand
- Rain sensor to reduce auto landscape watering (reduce utility and energy usage)
#Renewable energy is also sometimes called "clean energy", which is the resource taken from the natural environment or from a constantly replenished process. It's encouraging to use renewable energy because it takes the "free energy" from nature, although the manufacture process of renewable energy harvesting products may have adverse effect to the environment.
The commonly applied renewable energy includes the following, the selection of renewable energy type highly depends on the project site:
- #Wind Energy (wind turbine located in high wind area, natural wind speed drives the blade and feed to the electricity generator to produce renewable energy).
- #Hydroelectric energy (when water falling under gravity, or move at the fast speed, it drives the hydroelectric generator turbine blade and product energy).
There are many more innovative designs to reduce the energy consumption. We may be familiar with LED lighting, light tubes to direct sunlight to deeper indoor areas, VVVF lift with sleep mode, heat recovery systems, VSD pumps, VAV fans, ceiling fan with Air con system (hybrid air con), and many more. Every draw of energy is important to the building and overall energy saving target. So don't ignore any potential!
By default, building material costs 45% of the building construction cost (according to the LEED guideline), which makes building material as the most high cost single category in a building.
Material used in the building includes the building structure, interior finishes, external and landscape.
The general guide for sustainable building material is "reduce, reuse and recycle".
There are many materials better than concrete. A green building encourages you to reuse the building materials, select recycled or recyclable products, recycle construction waste and use materials help to create a healthier indoor environment.
It's encouraged to use low carbon concrete, which uses carbon negative manufacturing process, resolving serious environmental issues and minimising the carbon footprint of the concrete production. In addition, project should use concrete efficiently by reducing the amount of concrete per floor area, which is measured by the Concrete Usage Index (CUI).
The project should also reduce the waste generated during the construction stage, and recycle construction waste materials to reduce the disposal of in landfill or incineration facilities. Material sending to the recycled company will be recycled and repurposed. The following materials can be recycled: Concrete, Wood, Masonry, Cardboard, Steel, Aluminium, Furniture, Tiles, Land clearing debris, Carpets, and many more!
Recently, Green rating systems started to pay more attention to the sustainable rated systems rather than single types of green #material, to put a holistic view in encouraging the market integration.
A building project should verify the product raw material sourcing, ingredients and its life cycle impact analysis.
We have commonly seen the following material/product certifications to help us decide the sustainability effort put in for the material sourcing, manufacturing or delivering:
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.
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
We spend around 90% of the time indoor. The quality of the indoor air has long term effect on our health, productivity, and our mindset development. Indoor air quality directly relates to the Sick Building Syndrome (SBS).
Green building standard put strong emphasis on the indoor air quality, via the design guideline of conditioned supply air property, eliminating indoor and outdoor pollutants, and the regular maintenance.
1. Air conditioning and ventilation:
Studies showed a clear association between ventilation and the IAQ (Seppanen et al. 1999; Wargocki et al. 2000). The IAQ issue becomes more pressing after the SARS, Covid and events of local climate pollutions.
Based on our general understanding, good quality of indoor air has low concentration of CO2, and low level of harmful chemical emission from the indoor material. During the special hazy season, good indoor air quality also means to avoid outdoor pollution.
CO2 concentration is one of the key indicators to good IAQ. The outdoor air CO2 concentration is around 400ppm in the urban space. The CO2 in our indoor space should be lower than 1000ppm. Higher CO2 concentration in the indoor enclosed space will lead to drowsiness, headaches or poor productivity. To reduce the CO2 concentration, the building air conditioning system will supply fresh air (outdoor air) to the room. As it takes much more energy for air conditioning system to treat the outdoor air before delivering it to the room, many buildings are minimizing the fresh air intake, which may potentially compromise the indoor air quality. CO2 sensors are commonly used to measure the room CO2 concentration, to balance the IAQ and energy consumption.
2. Indoor and outdoor pollutants:
Indoor pollutants include building material, cleaning, painting products, and combustion sources (tobacco, heating and cooling appliances). Our typical concerns are Volatile organic compounds (VOC) in paints; insecticides and cleaning products; urea-formaldehyde in the pressed wood product; mod growth in wet and poorly ventilated areas.
To prevent outdoor pollutants, fresh air intake must be installed with high efficiency filters. MERV 14 filter is the industry high standard filter for outdoor pollution. As the high grade filter will cause the pressure drop for the fan, projects may only manually insert the MERV 14 filter when outdoor pollution occurs, while selecting the fan size with consideration of MERV 14 filter.
It is a continuous effort to maintain good indoor air quality. Project may conduct occupancy surveys to understand the feedback of indoor air quality and thermal comfort. Project can also consider a regular flush out to effectively remove the CO2 and bacteria build-up. Flush-out is to deliver higher amount of outdoor air (suggest 14,000 cubic feet/square foot) into the space.
4. Thermal comfort:
Air conditioning was perhaps one of the significant inventions of history.
- Lee Kuan Yew, Singapore's founding father.
With air conditioning system, we feel more comfortable in the indoor space, especially during hot summer season and anytime in tropical climate. "Comfort" is a very subjective term, and it depends on many factors base on individual preference. Many studies and research concluded 6 primary factors that may directly influence the thermal comfort, which are grouped into environmental factors and personal factors.
The 6 primary factors are: Air temperature, Air speed, Relative humidity, Mean radiant temperature, Clothing insulation, and Metabolic rate.
Industry use Predicted Mean Vote (PMV) model to advise the thermal comfort condition. This model was developed by Fanger and standardised in EN ISO 7730. PMV has 7 scales from -3 to 3, represent very cold to very hot. The "comfort" should be ranged between -0.5 to 0.5. Although many researchers reviewed this model, suggesting gender differences in thermal comfort, or regional preference (e.g. people in tropical climate prefer lower temperature), most of the projects are still using ASHRAE 55 PMV model as the general guideline for design.
A green building should minimise the water usage, and maximise the recycled water for non potable purpose.
The common water saving strategies include:
- Install low flow water fittings.
- Collect rain water (if feasible) and use it for irrigation, toilet flushing or general washing.
- Recycle the grey water for toilet flushing, irrigation, or general washing.
- Use city level recycled water source (if available, ie. Newater in Singapore).
- Choose local plants or low water consuming plants.
- Set up water sensors to prevent water leakage.
- For projects with cooling tower, maximise the cycles of water usage (suggest min 7 cycles of concentration with the effective filtration system to meet the water quality requirement).
- For projects with Air Handling Units (AHU), collect the condensate water.
- Benchmark to raise awareness and motivate water saving efforts.
Design and Innovation
Sustainable design carries strong growth-mindset. The designers and decision makers should design to last, design to benefit the users, design to create the learning platform, and design to create a long term benefit of the global sustainability movement.
Sustainable design is the DNA embedded in every designer's mind. Sustainability is a full integration and co-creating process. This integration process and the final project design are unique for each project. The project design should involve each discipline, including architects, engineers, QS, project manager, contractor, facility manager, the building owner and future users.
A green building works for the environment, rather than against the environment. It should make best use of the nature's wonderful gift in the benefit of the earth and people. We are taking the advantage to live and use earth's resources. It should also be our responsibility to feedback and look after the place that nourishes us. We do not need to wait for anybody or any authorisation, sustainability effort should be part of everybody's daily life.
Cheers to the Joy of being sustainable!