Problems with your HVAC system can manifest in a range of ways, all of which are worthy of concern. Whether the problems are financial or comfort related, they need to be dealt with.
Change is not always easy. When it comes to HVAC systems, this sentiment certainly holds true. Conventional variable air volume (VAV) systems have been used for a very long time, which gives them the ‘tried and tested’ value.
However, technology advances quickly, and HVAC systems are no exception. While a conventional VAV system may seem appealing, it is outdated. In the field of HVAC, developments have produced “DOAS + Radiant” systems, which far outperform conventional VAV systems in almost every way. Continue reading
Comfort is key. Being comfortable majorly improves performance and mental acuity.That is why HVAC systems are necessary – they should keep you comfortable, and thus, performing well.
However, not all HVAC systems are equal in their performance and functioning; some systems will be better than others, particularly in some climates. As I have mentioned previously, research is increasingly accumulating to show that the best HVAC system for efficiency, health, safety, and comfort, is the “DOAS + Radiant” system. Here, I will elaborate on why that is the case for comfort, i.e. how is a “DOAS + Radiant” system more comfortable than a conventional forced-air system? Continue reading
The maintenance of high indoor air quality (IAQ) is important in all buildings – the health and safety of the occupants require that the air is circulated to remove contaminants, and provide fresh air. The importance of IAQ becomes particularly evident when you take note of the fact that most people spend 80 – 90 % of their time indoors.
However, the conditioning of incurrent air into buildings can be tricky under some climate conditions, when treating incurrent air to meet standards for circulation around the building can be highly energetically and monetarily expensive. This is perhaps at one of its most pertinent in areas that are very humid (and often hot as well). For example, a study of commercial buildings in Thailand, a hot, humid region, showed that air conditioning could comprise 50 – 60 % of energy usage. Continue reading
This post reviews the technology options used for cool water generation and hybrid HVAC systems, such as Dedicated Outdoor Air Systems (DOAS).
The figure below shows a simplified schematic diagram for radiant based HVAC systems. A plant for cold water generation serves the radiant cooling surfaces in different spaces. An additional system is needed to:
- Provide outside air to spaces for ventilation
- To address the space latent loads
- To provide additional sensible cooling to make up the shortage of the radiant system capacity
In this post, we will pay particular attention to designing dehumidification capacity of a dedicated outdoor air unit and which safety factors to consider and which to avoid.
When designing various types of DOAS systems, safety factors are often used by engineers. With safety factors, many DOAS systems are purposely built larger than needed for normal usage to allow for emergency situations, unexpected loads, misuse, or degradation. However, excessive use can result in much larger-than-necessary equipment, inflated installed costs, and excessive energy use. Continue reading
When designing various types of DOAS systems, safety factors are often used by engineers. With safety factors, many DOAS systems are purposely built larger than needed for normal usage to allow for emergency situations, unexpected loads, misuse, or degradation. However, excessive use can result in much larger-than-necessary equipment, inflated installed costs, and excessive energy use.
In this post, we will try to determine the influence of safety factors on the design airflow of a dedicated outdoor air system. In the next post we will turn our attention to the design dehumidification capacity of a DOAS. Continue reading
As we have explored in previous posts on this blog, the Dedicated Outdoor Air System does not rely on new technology. It uses conventional HVAC equipment configured to condition outdoor ventilation air separately from return air from the building. A DOAS, therefore, requires two separate sets of equipment; one for outdoor air and one for return air. Continue reading
All throughout this blog we have looked at the many aspects of the Dedicated Outdoor Air System (DOAS) coupled with radiant heating and cooling. We have looked at its many benefits, its different components, how to design and optimise such a system. In this post, however, we will look at a theoretical example to demonstrate the multiple steps that need to be taken to model a DOAS with radiant cooling.
Note: we will be using the US imperial measurement system throughout this post as we are following ASHRAE guidelines. Continue reading