Technical Report snippets - Interview

For the technical report project, my team and I conducted an interview with Mr Reuben Phang, an Architectural Associate from DCA Architects via email. It consists of nine questions posted to him with regards to the project. The transcript is as follows below.

Question 1:  What kind of glass does an office building usually use? (Double glazed, single glaze,etc)

Answer: Office buildings in Singapore usually use curtain wall systems with low-emissivity double-glazed glass panels to control heat gain from the external to the internal air-conditioned spaces. The double-glazed panels also help with acoustics to ensure that sound transmission from the external is also controlled. 

Question 2: What are your thoughts on the energy usage for buildings that are made mostly of glass windows?

Answer: Office buildings usually have full curtain wall facade systems to maximize leasable area and the flexibility and views of the office areas (full-height vision glass panels). As office buildings are almost always air-conditioned (i.e. not naturally ventilated), the glass performance is very important to ensure that the building’s energy efficiency is reasonable. Otherwise, too much energy would be needed to cool down the internal spaces. While better performing glass (such as the low-E double-glazed glass) costs more, the energy savings (and cost) gained over time outweighs this higher up-front cost of the construction. 

Question 3: What are the current practices to curb with the glare and to ensure thermal comfort in such buildings?

Answer: All buildings have to comply with 2 requirements from the Building Control Authority of Singapore (BCA):

1. REGULATION ON DAYLIGHT REFLECTANCE OF MATERIALS USED ON EXTERIOR OF BUILDINGS (https://www.corenet.gov.sg/media/2013555/circular-on-regulation-on-daylight-reflectance-of-materials-used-on-exterior-of-buildings.pdf)

2. CODE ON ENVELOPE THERMAL PERFORMANCE FOR BUILDINGS (https://www1.bca.gov.sg/docs/default-source/docs-corp-news-and-publications/publications/codes-acts-and-regulations/retv.pdf)

Practices to comply with these requirements include calculations based on specifications for the facade materials and glass to determine if the proposed materials are within the allowable limits. 

Question 4: Do u have to worry a lot about the energy usage when designing high rise glass office buildings? 

Answer: Yes, building an energy efficient building is an authority requirement, and so it is an important priority in the process of design. 

Question 5: What are your thoughts on smart windows? is there a possibility that it’ll be widely used in the future? Smart windows like photochromic films and electrochromic glass.

Answer: I think there is a high possibility that smart windows that provide shading / darkening would be widely used, provided that the cost of these smart windows are reasonable. Currently there are already smart building systems with external or internal blinds being adjusted based on the weather / environmental conditions. This reduces the amount of energy wasted on over-cooling spaces. 

Question 6: What type of buildings are suitable to use overhangs and are they usable in all situations?

Answer: Overhangs and external sun-shading devices are suitable for use in all buildings in terms of energy efficiency. However, the effectiveness of these devices or overhangs are dependent on site conditions such as building orientation, sun path and angles, and building setback requirements. The design of the facade is also an important consideration as these elements are usually prominent structures aesthetically. 

Question 7:  What are the factors considered when sourcing for materials of windows that are used in high-rise office buildings

Answer: For glass: Visible light transmittance (VLT) values, Shading coefficient values, U-values (measurement of thermal transmittance). 

Question 8: How do you determine the best material for commercial use? For example, integrity of the material? Density?

Answer: First consideration would be the design intent - opaque vs transparent vs translucent? Full-height glass vs half-height glass? This plays a big part in selecting the “best material”. Next would be to consider the specifications of the materials (see answer to question 7). An additional consideration is also how difficult it is to construct - that has implications on cost and productivity. For a commercial building, this is very important as it affects the financial viability of the project. 

Question 9: What do you think of the implementation of solar films on windows? Is it feasible or unprofitable?

Answer: I think that low-emissivity coating for the glass is a more effective and efficient method in comparison with solar films. Solar films are suitable for smaller scale projects such as homes, but in larger scale projects they are hard to maintain and have issues with durability. As such, they should only be used as a last resort (i.e. in cases where new or full replacement of glass is not feasible).