The goal of is to provide useful information related to heating, ventilation and air conditioning (HVAC) for people around the world, particularly homeowners, junior engineers and technicians. I believe that well-informed people can design and operate air conditioners more efficiently and thus, the environmental impact of air conditioners can be reduced.

My name is Yu Chang Zhen. I live in Malaysia, a hot and humid country. I have more than 7 years of practical working experience in the HVAC industry. I’m also a supporter of the mission to accelerate the world’s transition to sustainable energy. Hence, I want to utilize my skills and experience to contribute to the environment through blogging.

“Online learning is a great way for people around the world to gain access to useful information thereby improving their skills and making the world a better place.”

Within my area of expertise, I found that blogging is a great way to provide great value to society. I’m able to teach thousands of people of different ages and professions from around the world on a daily basis through blogging. Hence, I’m excited to share with you my journey.

Why I Started

For many years, I encountered many poorly-designed air conditioning systems that are wasting a significant amount of energy while making people’s life difficult. At the same time, I also have seen many junior engineers struggling to keep up because of insufficient guidance.

While mobile phones and laptops have rapid technological development, the construction industry is still doing the same thing every day; people are still managing work manually using papers and whiteboards at the construction site.

Although there are many handbooks, guidelines, courses and seminars out there, most fresh graduate junior engineers simply can’t afford them. Furthermore, many of the handbooks are priced in US dollars. As a result, engineers from developing countries are almost never going to be able to afford them. Hence, globally, many people still don’t have access to some of the most basic knowledge about HVAC. So, how can we expect the air conditioning systems there to be running efficiently?

I was once a fresh graduate that has little to no idea what I was doing at work. So, I understand the struggles that many junior engineers are facing every day. Thus, I think it is meaningful that I provide easy-to-understand information on the internet for people to learn efficiently and affordably. I do find ways to monetize my work so that I can sustain myself but I promise to make it affordable.

Environmental Contributions

Apart from providing useful information to homeowners and junior engineers, I also want to contribute a little bit to the environment because experts said it is inevitable that Earth is going to warm up much more than the world anticipated unless everyone joins forces to reduce carbon emissions. So, I try to contribute and I also encourage my readers to do so. As a result, my product recommendations often lean towards high efficiency.

Heating and cooling in buildings are one of the major contributors to global warming. However, inefficient heating and cooling systems are making things worse. According to IEA research, most people are not using the most efficient air conditioners. They projected that space cooling energy demand will be cut by half if most people are using efficient air conditioning systems.

“The problem is, today’s consumers are not buying the most efficient ACs.”

International Energy Agency (IEA)

In addition, IEA also expects air conditioners to be the second-largest source of global electricity demand growth after the industry sector and the strongest driver for buildings by 2050.

I’m hoping that my blog articles are able to teach more people about HVAC systems so that more heating and cooling systems can run efficiently and thus, the overall power consumption can be reduced and ultimately, carbon emissions can be reduced and global warming can be turned around.

Furthermore, I also sign up to Stripe Climate where I fund carbon removal from a portion of every purchase made on through Stripe payment gateway. See aircondlounge’s contribution here.

About Yu Chang Zhen

I started my first job as a Project Engineer in a small company that specialized in building district cooling plants with thermal energy storage back in the year 2013. I was assigned to assist a few project managers on tender, design and submission work. Back then, I mostly just follow managers around meeting clients and taking notes. After a few months, I learned to become more independent and that’s when I and two other project engineers, who joined the company about the same time as me, were assigned to a hospital energy audit and retrofit project.

While working on the hospital project, I got to use many cool measuring devices such as temperature and humidity data loggers, ultrasonic flow meters and pitot tubes. Back then, I was primarily responsible for data analysis and reporting. In the following year, I worked on a primary school air conditioning system construction project. After the project was completed, I decided to move on to another company.

Nearly two years after my college graduation, I still worked as a Project Engineer. In my new company, I was assigned to work on two luxury high-rise residential towers simultaneously. But, the project had already started and we were behind the schedule. Thus, I was having a very difficult time trying to adapt and catch up with the schedule. At that time, I was managing more than 30 direct workers and two sub-contractors at peak with over a thousand air conditioners and mechanical fans waiting to be installed and commissioned.

It was very stressful because I barely have any experience in high-rise building construction. I was staying up until late at night almost every day during the commissioning stage. Furthermore, I had to do many tests by myself as workers were generally unable to handle instruments, causing delays on some of my RFIs and submissions.

Out of all, the bomba test is the most critical part for me. I teamed up with a few general workers to finish up the entire smoke spill and pressurization system as my supervisor had to bring another team to commission air conditioners for the residential units.

Fortunately, we were able to pass the bomba fire safety test in one shot and got all air conditioners tested and commissioned thereby minimizing the delay and ultimately obtaining the certification of practical completion (CPC) for the project. Although the project was very difficult for me, I grew a lot since then. I learned time and stress management as well as people and relationship management.

In the same year, my colleagues and I went to Beijing, China to attend one of the largest HVAC&R exhibitions in the world. The exhibition center is so big that we had to split into 4 teams and stay for 3 days. Every night, we’ll exchange the information and knowledge gained from each team.

Since we are in China, we wouldn’t want to waste it. So, we took the opportunity to go around Beijing and visited some tourist places like Great Wall, and Muzeum before flying back to Malaysia. I have many great memories of the trip to Beijing and we learned so many new things from the HVAC&R exhibition. Till today, I still keep in touch with most of my ex-colleagues.

Back to my work. After the two residential towers were handed over, my service team took over and I was transferred to work on another high-rise building but this time, it was an office tower. Remarkably, I was told that it is the first-ever hybrid chiller project in Malaysia. It has a whopping 54 units of hybrid chillers sitting on the roof. My colleagues and I always talk about it during tea breaks. The project also involved a few industry experts to guide all of us involved the project on energy efficiency and green building codes. I was lucky to be able to join a few factory visits with them and it was eye-opening for me.

After more than 4 years of working, I was promoted to become a Senior Project Engineer. I was doing multiple design projects including value engineering work, 3D Revit drawings production and the installation of VRF air conditioning systems for high-end retail stores. Meanwhile, I also reported directly to the managing director on business development work. Though I like my company at that time, I decided to challenge myself a year later.

I took an offer from another company and became a Project & Service Manager at the age of 28 where I was working primarily on hot water heat pump systems. For about 2 years, I was serving hundreds of customers every week, solving their hot water and heat pump issues before I decided to quit and start this website.

There is so much more I want to share but this is getting too long. If you want to know more details about me and what I do previously, you can check out my LinkedIn profile and follow me on various social media platforms. Also, you can subscribe to my newsletter using the signup form I’ve prepared around my website to get notified of new posts and updates on aircondlounge. Thank you.

Yu Chang Zhen

Project Experiences

I’ve handled not many projects compared to people who worked in the HVAC industry for 10-20 years. However, I manage each and every project in detail; almost every aspect of the project from costing to commissioning and after-sales service, in Malaysia.

Menara TCM

A 32-storey premium office building designed for GBI and Leeds gold accreditations that consists of multiple office floors, a banquet hall and a food court.

  • Evaporative hybrid chiller system
  • Chilled water air handling & fan coil unit
  • Variable air volume system
  • Ultra violet germicidal irradiation system
  • Pre-cool fresh air & CO2 sensor system
  • Smoke spill & pressurization system
  • Carpark CO sensor system

Tropicana Gardens

Two blocks of luxury high-rise condominium with 4 basement carparks, two recreation floors and multiple types of residential unit.

  • DX split unit
  • Multi-split system
  • Residential VRF system
  • Ducted fan coil unit
  • Kitchen & toilet exhaust system
  • Smoke spill & pressurization system
  • Carpark CO sensor system

Village Grocer @ Tamarind Square

A premium supermarket that has high standard for the aesthetic of mechanical services.

  • Air-cooled VRF AHU system
  • Ductwork
  • Noise and vibration control
  • VRF centralized control system

BookXcess @ Tamarind Square

A large bookstore consists of a study area, a children area and common space for shoppers.

  • Air-cooled VRF system
  • Fresh air system
  • VRF centralized control system
  • Condensation prevention

SJK (c) Wangsa Maju

A primary school consists of office rooms, common space and a 11,000 sqft hall that can hold 1000 students.

  • Air-cooled split AHU system
  • Ductwork
  • Noise and vibration control


I don’t spend a lot of time attending courses and seminars to get certificates for the sake of getting certified and the proof of credentials. These are what I have.

HVAC System Knowledge

From my work, I learned about many air conditioning systems, both residential and commercial. Unfortunately, I didn’t have much experience in industrial applications. Nonetheless, these are the systems that I know and had experience with.

  • Chiller System – Evaporative hybrid chillers, water-cooled chillers, air-cooled chillers, cooling towers & pumps.
  • VRF System – Air-cooled VRF condensers, central monitoring system, VRF troubleshooting, VRF copper pipe, VRF AHUs & water-cooled VRF systems.
  • DX Split System – Split units, multi-split systems, ducted split systems, AHU splits.
  • Exhaust System – Toilet exhaust, kitchen exhaust & exhaust for mechanical rooms.
  • Smoke Extraction System – CO sensors, fire compartmentation, fire dampers and fire curtains.
  • Pressurization System – Staircase pressurization, lift lobby pressurization, VSD fans, motorized fire dampers and differential pressure sensors.
  • District Cooling Plant – Thermal energy storage tank, load profile and underground pipes.

In addition, I also have a few years of experience with hot water system.

  • Heat Pump System – Air source heat pumps, water source heat pumps and hot water storage tanks.
  • Water Heaters – Instant water heaters, storage water heaters and heat pump water heaters. – HVAC Education Site for the World