Boschendal: indirect evaporative solution delivers in extreme conditions

By Ilana Koegelenberg

Boschendal’s stunning Olive Press venue had a unique challenge in terms of its cooling requirements: the one side of the venue was entirely open — not to mention ambient design conditions in excess of 40°C! But there was a solution … and a hyper-efficient one at that, too.

BoschenDPS

Boschendal, located in the Drakenstein Valley in the Western Cape, is one of the oldest farms in South Africa, founded in 1685. It is the second-oldest wine farm in the country.

In 2013, Boschendal was acquired by new owners, led by Sam and Rob Lundie, with the intention of rejuvenating this magnificent property. Over the past four years, they have attracted a team of talented people who share their dream of making Boschendal into a top agricultural farm; a farm that produces sought after naturally produced food and great wines, and a farm where the natural environment thrives and local communities prosper.

As such, the Boschendal estate has spent a lot of money over the past few years upgrading its facilities. In doing so, they have also built a beautiful multifunction venue called the Olive Press on their estate to host wine lovers from all over the world.

This elegant new wedding and function barn offers exposed natural poplar roof trusses, floor to ceiling glass doors, and stunning views over meadow gardens to the Groot Drakenstein Mountains. The double-volume space is the perfect combination of contemporary and organic.


On 3 March 2015, the ambient temperature reached a maximum of 42°C. During this time, the Climate Wizards were supplying air at 16.2°C and maintaining the room at a comfortable 23°C.


With Africa’s sizzling summer conditions, especially in this region, the owners were looking for a cost-effective air-conditioning system that could cool their venue as efficiently as possible.

CLIENT BRIEF

The following HVAC project specifications were provided to the specifying engineers:

  • ASHRAE design conditions of 33°C dry bulb and 20.2°C wet bulb
  • Operating hours: 8:00–22:00 (seven days per week)
  • People in venue: 400 people @ 75W/person (30kW total load)
  • Staff: 10 people @ 50W/person m2 (0.5kW total load)
  • Indoor temperature: 25°C
  • Ventilation: 2.5ach
  • Doors to veranda: open
  • Total cooling requirement: 137kW (for inverter air conditioning and fresh air)
  • Outside air: 10ℓ/s/person.

CHALLENGES

The challenges the consultants faced were:

  • Ambient design conditions in excess of 40°C;
  • Venue designed to hold functions for more than 400 people, with a high outside air requirement; and
  • One side of the building completely open, offering scenic mountain views as a highlight of the guest experience.

The indirect evaporative cooling units supply 100% outside air. The six Climate Wizard units installed outside the Boschendal Olive Press venue. The impressive, open multifunctional venue that is cooled by the units. The tops of the Climate Wizard units are barely visible outside the venue.

FINDING THE RIGHT SOLUTION

Philip Briel Architecture and Urban Design headed up the project and appointed Thermo-dynamics as the HVAC&R contractors.

The team considered various options before making their decision. Originally, they looked at evaporative cooling, but this was not a feasible option, explains Craig Bransgrove of Thermo-dynamics. A variable refrigerant flow (VRF) system was also considered with ducted units inside the roof. But with the venue being open, the required heat rejection capacity would have to be so high to be effective that the cost would skyrocket. The team did a calculation and worked out that another R400 000 would have to be spent just to upgrade the power supply to support this solution.

This all happened during 2014, when Seeley’s Climate Wizard started making its appearance on the local market. It was a risk on both sides as Seeley offered to put the units in under the guarantee that if they did not work, they would take them out again — something that is unheard of.

Although the system is more expensive than the VRF because of the added cost of the power upgrade, it would prove 30% cheaper in the end. In fact, the system draws so little power it can be run off a generator if need be or even off solar.

Seeley’s Climate Wizard indirect evaporative air conditioner was selected for the following reasons:

  • Capable of cooling large open spaces;
  • Delivers the legislated fresh air requirement for the venue in a cost-effective way; and
  • Supplies 100% outside air.

The Climate Wizard inherently handles the outside air cooling load and also blows any latent load out of the room instead of recirculating it. It also handles the heat load and only has to cover the 60kW internal sensible load, compared to the 137kW load required with a vapour compression air conditioner.


A 2.6-year return on investment could be received by offsetting the capital cost and the annual saving of power (kWh and demand tariffs on kVA).


Eventually, six Climate Wizard units were installed with a cooling capacity of 60kW and coefficient of performance (COP) of 5.7, with only 10.8kW of power required. The units were crane lifted onto the roof space at the back of the venue where they are barely visible from the ground.

In terms of water, these units, running at full load capacity, only use about 15ℓ/ hour which is minimal when considering that flushing a toilet uses 22ℓ for each flush.

OTHER REQUIREMENTS

But it wasn’t quite as easy as simply selecting a product and sticking it in. There was a requirement for the system to be as quiet as possible. As such, a sound engineer from Johannesburg (Sphere Sound Solutions) was flown in to make sure the installation, when positioned on the roof, would not affect the sound inside the venue.

Aesthetics was also high on the list of priorities. Located on a heritage site and being such a prestigious venue, the system had to be as unobtrusive as possible. The team carefully considered the design of the building to ensure that the units were hidden away and almost unnoticeable.

Following the success of the units at the Olive Press, two more Climate Wizard units have been installed at Boschendal Wine Estate’s restaurant. The air grilles on the walls are hardly noticeable if you are not actively looking for them.No matter the time of year and the temperature outside, the Olive Press venue will always be the perfect temperature inside.

RESULTS AND SAVINGS

Despite being completely open on the one side, the HVAC solution is sufficient to keep the room at design temperature, even in extreme ambient temperatures above 40°C. Even on the adjacent balcony area there is a significant difference in temperature compared to outside as the cooled air reaches here too.

Boschendal Wine Estate’s owners have been very impressed with the results over the past three years since installing the system. Everything has been carefully monitored and controlled to ensure that the required conditions continue to be met.

Some noteworthy results include:

  • Over a 10-day period (10–20 March 2015), an average Climate Wizard supply temperature of 21°C was achieved, whilst using only 10.8kW of power, with one side of the building completely open, delivering 100% fresh air;
  • This solution was 30% cheaper to install as part of a new building site;
  • The infrastructure savings with Climate Wizard were almost R0.5-million, as the venue did not need to upgrade the electricity supply to meet the proposed air-conditioning power requirements; and
  • A 2.6-year return on investment could be received by offsetting the capital cost and the annual saving of power (kWh and demand tariffs on kVA).

The savings, as compared to an inverter HVAC system, were calculated as follows:

   Climate Wizard  Inverter AC  Savings 
 Running amps  15A  70A  55A
 Maintenance  R300/m  R2 000/m  R1 700/m
 kW   10.8kW (COP 5.7)  31kW (COP 2.9)  20.2kW

As can be seen, the maintenance costs of the system are minimal. The units are serviced twice a year and the filters cleaned regularly. The advantage of this system, though, is that you do not need a qualified HVAC technician for the service as it basically involves cleaning out the filters, testing, and switching them on.

“We haven’t had a breakdown or an issue in three years,” says Bransgrove. “We haven’t even had to replace any parts.” This would have been an entirely different story if compressors had been involved, considering the ambient temperatures above 40°C!

EXPANDING

Following the success on the Olive Press installation, two more Climate Wizard air conditioners have now been installed on the Boschendal Wine Estate, this time at the estate’s restaurant where the hidden units perform their cooling task silently and efficiently.

LIST OF PROFESSIONALS

 Owner   Boschendal 
 Architect / Designer  Philip Briel Architecture and Urban Design: Jonathan Green
 Consulting engineers  Mechanical  De Villiers Sheard
 Sound   Sphere Sound Solutions
 Contractors  HVAC & R  Thermo-dynamics 
 Product suppliers  Indirect evaporative coolers  Seeley International 
 Diffusers   Trox

Click below to read the January 2018 issue of RACA Journal

RACA JAN2018

 

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