Mechanical Technology February 2015

⎪ Heating, cooling, ventilation and air conditioning ⎪

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

F 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 2 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.

“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

26

Mechanical Technology — February 2015