Mechanical Technology February 2015

⎪

Heating, cooling, ventilation and air conditioning

⎪

Mechanical Technology — February 2015

rom its 30-year history as RPP

Consulting Engineers, De Bod

and his team bring extensive

experience in mechanical instal-

lations for casinos, shopping centres,

hotels, leisure developments, office build-

ings, data centres, district cooling and

heating plants, green building projects,

building management systems and apart-

ments. “We are as busy as we ever were.

All of our historical clients continue to

deal with us as if nothing had happened,

which is a nice compliment for us and

for the work we did as RPP,” says De

Bod. “The entire engineering team from

RPP came across to the WSP offices in

Bryanston and have slotted in alongside

the existing WSP HVAC engineers.

“We were brought in to promote new

business opportunities for clients willing

to invest a little more in their mechani-

cal and HVAC installations, in return for

improved energy efficiency and better

environmental credibility,” says De Bod.

“Air conditioning is historically the largest

power consumer in commercial buildings

and building managers and owners have

realised that increased Eskom electric-

ity tariffs are hurting pockets. So, after

many years of having to convince many

clients of the merits and long term value

of energy efficient technologies, more

investors are realising the benefits of in-

stalling modern, energy efficient systems,

maintaining their systems and choosing

capable management personnel. Saving

electricity is no longer only about the en-

vironment; it’s now about saving money.

By running a building’s air conditioning

system more efficiently, the operating

costs can be dramatically reduced and

the pay back periods have become much

easier to justify,” he argues.

“In 2007 we tendered for a 22 000 m

building in Sandton for a banking client

that requested an air conditioning system

with reduced power consumption. Back

then, few people believed that invest-

ments in energy efficiency were cost ef-

fective, but we took the risk and put out a

tender for a design that was cutting-edge

for the time. The developer also took a

risk and chose to invest in this slightly

more expensive state-of-the art system.

Today, that building uses about half of

the energy of other buildings in Sandton,

and the decision to pay the higher price

is looking like the most sensible financial

decision made by anyone at that time,”

De Bod relates.

“Numerous buildings across the

country are currently installing heat

recovery wheels and premium efficiency

chilling systems. Energy efficiency and

green building philosophies are now

mainstream trends. But we haven’t just

jumped on this bandwagon. We have

been applying energy efficiency principles

for a very long time. The difference, now,

is that clients are listening instead of

laughing,” he adds.

Notable new projects currently being

undertaken by De Bod’s WSP team in-

clude two projects that are both targeting

LEED (leadership in energy and environ-

mental design) ratings from the US green

building council. Nearing completion is

an office building being developed in

Midrand for a Swiss pharmaceutical gi-

ant. “This building is targeting a LEED

Silver rating, which is approximately

equivalent to a 4-Star rating by the

Green Building Council of South Africa

(GBCSA),” says De Bod.

Features included in the HVAC design

are partial ice storage, heat recovery

wheels and very high efficiency multi-

energy air-cooled chillers. “Traditional

chillers produce chilled water and reject

the heat via either air cooled or evapora-

tion-based cooling towers on the roof. For

heating, a heat pump does the reverse, in

that it produces hot water while absorb-

ing heat from the environment.

Following the acquisition of RPP Consulting Engineers by the WSP Group

in April last year,

MechTech

talks to Pieter de Bod, now the director of WSP

Mechanical Division, about the merger and the modern HVAC capabilities

that are now being undertaken by his reinforced team.

Modern HVAC trends in

commercial buildings

“Multi-energy chillers can operate in

both cooling and heating mode, indepen-

dently and at the same time,” De Bod

explains. “When generating chilled water,

the rejected heat that would normally be

lost to the atmosphere is recovered in the

form of hot water, while when in heating

mode, cooling is recovered. This helps

to cater for the diversity of demand from

the different zones in a building, where

south-facing rooms might need heating at

the same time as the north-facing rooms

require cooling. These systems delivers

high performance efficiencies,” he adds.

To take advantage of cheaper off-

peak electricity and to reduce maximum

demand tariffs, these chillers are being

used in the Midrand office block to make

ice at night, which is stored in open tanks

before being melted to supplement cool-

ing demand during peak times in the day.

“This is our first LEED-rated building and

it should be complete by April. We have

also recently been awarded a multi-story

building in Centurion, which will use

similar technology, but on a much bigger

scale,” De Bod says.

“These developments will also be

future-proofed for the possible addition

of a tri-generation plant, which needs a

large and reliable gas supply. When gas

arrives to the site, the tri-generation op-

tion will become more feasible,” he adds.

Another key trend brought about by

the demand for better energy efficiency is

to refurbish older commercial buildings.

“Technology was very different 30 years

ago. We saw extensive use of electrical

resistance heaters in the industry, for

example, which are a ‘no-no’ now. Air

conditioners were typically run at fixed

speed, while today, we see much greater