The Emerald – Complete Luxury Living And Facilities

The DX coil is needed to control both temperature and assist with achieving acceptable humidity levels within the space. The American Society of Heating, Refrigerating and Air-Conditioning Engineering (ASHRAE) – HVAC Applications  – Chapter 6 that specifically relates to natatoriums or indoor swimming pools, documentation provides significant insights and guidance towards the engineering required in these applications in terms of specifications and sizing of units – particularly when heated pools are involved. These standards also provide substantial guidance on humidity control, ventilation requirements, air distribution, duct design, pool water chemistry and evaporation rates.

The basement parking area contains a simple extract ventilation system in the form of jet fans under soffits that operate as an on/off solution linked to various CO sensors located in the space. These sensors continuously monitor the CO levels and once they reach a certain pre-set value, the fans switch on and run until the space reaches a certain level of CO that is again acceptable – which then triggers the fans to switch off automatically.

The laundry area (also located in the basement) includes a simple extract ventilation system to assist in removing the heat generated from the tumble dryers and ironing stations. A split unit is also installed to help with overall space cooling and for comfort of the laundry staff.

The shower/changeroom/toilets (located on two levels), as well as the café kitchen include standard air extract systems. The reception area and upstairs offices are provided fresh air through a slim design diffuser and split wall unit respectively.

The future provision for the dedicated IT room included installation of two mid wall split units.

The air terminal selection was through co-ordination with the architects where the preference was linear slot diffusers or small diffusers in order to ensure the aesthetics aspects were met.

Project challenges and solutions

The lobby area and café counter supply and return air terminals.

As it happens with any project of such scale, challenges arise that must be overcome. One such challenge was the limited plantroom space that was allocated. Essentially there was no way of increasing this area purely because of the perimeter location of the building, so we had to make the design work with what was available. Needless to say it was quite a tight squeeze. We had to spend time on the exact positioning of the equipment in the plantroom and to make sure our model was perfectly to scale. The modelling had to match precisely to the suppliers’ dimensions of the AHU, condensing units and ducting before placement on site. Here we worked closely with the suppliers to communicate the space limitations and matching of equipment to fit.

The most significant challenge of this project, however, was definitely the dynamics involved in the gym/indoor pool area that shares the same climatic conditions as a double volume space. What essentially happens here is that this space experiences both heat and a lot of added humidity from the pool water (that is heated) which in turn is rejected into the air. The gym area, being located on the upper mezzanine level above the pool, shares the same volume while it is served by its own multiple VRF-connected diffuser units.

What was experienced shortly after commissioning the systems was that because of the very high humidity in this area, condensation formation occurred on the diffusers in the gym because of the the difference between the supply air temperature from the individual units versus the dewpoint temperature of the shared pool room space. Finding ways to modify the air terminals and system control settings to reach a point where the dewpoint temperature and supply air temperature in these spaces don’t create condensate was the biggest technical challenge by far.

Unique elements

Having developed a personal natural liking for leasure and lifestyle type projects, these usually each have a unique application to start off with and are fun to be involved in – particularly when you get to take on the challenge of projects including high-end facilities and finishes such as this site.

Here the unique elements were directly linked to the purpose and function of the overall development and facilities, including the designing and correct system sizing related to an indoor heated pool area. This is definitely not something one gets to participate in every day, and I will add is also an exercise that you can easily burn your fingers on.

I would strongly advise other engineers taking on applications of this nature to really do your homework properly. One needs to make sure you know the background and all factors of influence. There are a number of guidelines through ASHRAE and other literature sources to consider to ensure adequate knowledge of best practices and how heated pools can have an impact in other systems’ functions.

Impact on energy efficiency

In terms of energy efficiency, the VRF system in itself is a very good, energy efficient system compared to conventional split units as a solution.

Another element of additional efficiency that was included in this project was that the pool system, which is a very large capacity AHU, has a heat recovery wheel which assists with dropping the load on the capacity of the unit itself, because the heat wheel pre-cools the incoming fresh air to the system and this is especially important in this case where the pool unit is a full fresh air unit bringing in a lot of air. This addition definitely reduces the load on the coil which creates better efficiency.