Tech Talk

EEC first introduced the DEECS – Dedicated External Environmental Control System in 2000 through the Hamad Medical Complex (HMC) project, a 1,500-bed tertiary hospital in Qatar. The objective was to achieve stable and consistent indoor environmental conditions, independent of highly fluctuating outdoor climates. Qatar’s climate is characterized by extremely hot and dry daytime conditions, followed by cool nights with very high humidity. This combination had previously resulted in serious challenges within hospitals, including excessive indoor humidity, mold growth, and elevated infection rates.

When integrated with HAU 2000, a specialized air-handling system designed specifically for operating theaters, the DEECS concept demonstrated outstanding performance. As a result, Hamad Medical Complex has been widely recognized as one of the best hospitals in the GCC in terms of indoor environmental quality—a distinction it continues to uphold today.

In 2003, this technology was introduced in Thailand for the first time at Siriraj Piyamaharajkarun Hospital, a 345-bed facility with a total floor area exceeding 200,000 square meters. The project became a benchmark for modern hospital design, setting new standards for indoor air quality (IAQ) and influencing hospital design practices across Thailand. While the term DEECS gradually faded from common use, the core principles remained. Following the publication of the ASHRAE Design Guide for DOAS – Dedicated Outdoor Air Systems in 2017, the terminology DOAS became globally recognized and widely adopted.

Today, DOAS is an internationally accepted technology, applied not only in healthcare facilities but also across a wide range of building types. Its ability to precisely control indoor environmental conditions, maintain superior indoor air quality, and significantly reduce energy consumption has made it a key component of high-performance buildings. In particular, the separation of outdoor air systems from conventional air-conditioning systems allows fresh air to be delivered directly to the breathing zone, without passing through cooling terminals.

Beyond DOAS, EEC has consistently led the adoption of advanced building environmental technologies, including Displacement Ventilation, Floor Radiant Cooling, variable-speed and variable-flow systems, and ductless air-conditioning solutions. These innovations have been implemented to enhance system efficiency while substantially reducing energy consumption.

Ductless air-conditioning systems can be effectively applied to convention and exhibition halls, offering significant advantages in both capital and operational efficiency. By eliminating the need for large air-handling units and extensive long-distance ductwork, these systems substantially reduce installation costs, structural requirements, and system complexity. The absence of large ducts also leads to a meaningful reduction in fan energy consumption, which is a major contributor to overall energy use in large-volume spaces.

In addition, ductless systems provide superior acoustic control, minimizing noise typically associated with conventional air-distribution systems. This creates a quieter and more comfortable indoor environment, well suited to conferences, exhibitions, and large-scale events.

Another key advantage is the ability to operate the system selectively by zone, allowing cooling to be provided only in occupied areas. This zoning flexibility enhances operational efficiency, reduces unnecessary energy use, and aligns well with the highly variable usage patterns of convention and exhibition halls.

In parallel, EEC pioneered the introduction of District Cooling Systems (DCS) and Thermal Energy Storage (TES) in Thailand in 2003, starting with the Government Complex Commemorating His Majesty the King’s 80th Birthday Anniversary. This initiative later expanded to urban-scale district cooling at The Forestias in 2015, followed by Cloud 11. These developments gave rise to a new energy business model—chilled water as a service—shifting the market paradigm from decentralized, split-type air-conditioning toward centralized chilled-water systems.

This transition has played a significant role in mitigating the urban heat island effect, reducing excessive refrigerant usage, promoting environmentally friendly refrigerants, and lowering peak electricity demand, overall energy consumption, and carbon emissions.

These achievements represent only a portion of EEC’s long-standing commitment to becoming a leading Thai engineering firm that actively drives the construction industry and national development in the right direction. This vision has remained consistent since the company’s founding, with the goal of elevating standards in environmental performance, energy efficiency, and fire and life safety.

EEC also takes great pride in its pioneering role in advancing fire safety standards in Thailand. Long before the enforcement of the 1992 Building Control Act, EEC designed numerous buildings equipped with automatic fire-sprinkler systems, compliant means of egress, and properly designed fire escape staircases. The firm also contributed to the development of mandatory annual building inspections, which have since become a national standard for building operation and safety.

Water management has always been another core focus of EEC’s design philosophy. This includes efficient water use, wastewater recycling and reuse, and flood-risk mitigation. EEC is well known for its strict policy of avoiding the placement of critical mechanical and electrical rooms in flood-prone basements—a design approach frequently praised by building owners and facility managers for its long-term operational reliability and ease of maintenance. Even issues often overlooked, such as restroom odor control, are carefully addressed through solutions such as odorless floor traps.

Finally, EEC has championed the design philosophy known as Climate Design, founded on the belief that urban heat is largely a human-made problem—and therefore can be mitigated through thoughtful design. The objective is to reduce the experienced temperature of occupants by improving the surrounding microclimate. As outdoor environments become more comfortable, the reliance on mechanical air-conditioning naturally decreases.

This approach has been successfully implemented at The Forestias, where studies have shown a reduction in operating temperature of approximately 3–5°C. The results confirm that Climate Design is a scalable strategy with strong potential for application across many future developments.