More: MEP Systems

MEP Systems for Existing Mid-Rise Office Buildings in North Texas

Mechanical, electrical, and plumbing (MEP) systems represent the operational core of any commercial office building. In North Texas, mid-rise office buildings (typically 4–12 stories) encounter unique environmental stresses—from extreme heat, strong UV exposure, and wide seasonal temperature swings to occasional freezing events. These conditions heavily influence system design, maintenance, replacement strategies, and tenant improvement modifications. This page details the major MEP system types found in North Texas mid-rise office buildings, along with subcategories, components, and construction considerations specific to our region’s commercial building stock.

1. MECHANICAL SYSTEMS (HVAC)

North Texas has a long cooling season with high humidity and peak summer temperatures often exceeding 100°F. For existing mid-rise buildings, mechanical systems must deliver reliable cooling, maintain air balance, and support today’s dense occupancy loads and equipment.

Most mechanical systems fall into several categories:

A. Rooftop Units (RTUs)

Many mid-rise buildings, especially 1980s–2000s construction, use packaged rooftop units that supply conditioned air through vertical shafts.

Components:

• Compressors (scroll or screw depending on tonnage)
• Condenser coils and fans
• Supply/return fans
• DX cooling coils
• Economizers
• Controls (legacy or digital BAS)

North Texas Considerations:

• High ambient temperatures reduce efficiency; oversized condensers or enhanced coils may be required.
• Hail protection screens are common due to frequent hailstorms.
• UV exposure necessitates coatings and robust insulation.
• RTU replacements require crane coordination and careful roof/load evaluation.

B. Chilled Water Systems

Found in higher-end or larger mid-rise buildings.

Components:

• Central chillers (air-cooled or water-cooled)
• Cooling towers (if water-cooled)
• Chilled-water pumps
• Air-handling units (AHUs)
• VAV boxes at tenant spaces

North Texas Considerations:

• Water-cooled systems require freeze protection measures for exposed lines.
• Cooling towers must withstand algae growth and high evaporation cycles in hot seasons.
• Chillers must be sized for high heat loads from glass façades and west-facing exposures.

C. Variable Air Volume (VAV) Distribution

VAV systems dominate mid-rise TI work because floor plates often require frequent reconfiguration.

Components:

• VAV terminal boxes with reheat coils
• Flex duct and supply diffusers
• Return air through ceiling plenums
• BAS controls to manage airflow

Challenges in North Texas Buildings:

• Reheat coils may overload older electrical systems.
• Tenants often demand more zones to address hot/cold spots caused by solar exposure.
• Older buildings have insufficient outside-air intake; TI projects may trigger ventilation upgrades.

D. Split Systems / Mini-Splits

Used for:

• IDF/MDF rooms
• Electrical rooms
• After-hours cooling for certain tenants

Concerns:

• Condenser placement must account for hail risk and heat rejection.
• Refrigerant line routing in post-tensioned slabs requires scanning before penetration.

E. Controls & Building Automation Systems (BAS)

Older pneumatic controls are still present in many Dallas/Fort Worth mid-rise buildings.

Modernization Includes:

• DDC controls for AHUs, VAVs, RTUs
• Monitoring and trending for maintenance and energy savings
• Remote access capability for building engineers

Upgrades often coincide with major TI projects to balance new floor layouts.

2. ELECTRICAL SYSTEMS

Electrical systems must support dense technology loads, modern lighting, and tenant-specific equipment. Many mid-rise buildings constructed before 2000 were not designed for today’s plug loads, necessitating panel upgrades and distribution improvements.

A. Main Electrical Service & Distribution

Typical mid-rise buildings use:

• 480/277V service for HVAC and lighting
• 208/120V panels for receptacle loads
• Step-down transformers located in electrical rooms

Upgrades May Include:

• Panel replacements due to age or insufficient capacity
• Installation of new transformers to serve high-density suites
• Riser upgrades to support additional tenant demand

In older buildings, obsolete equipment brands (e.g., FPE, Zinsco, some early Square D units) may require replacement for safety.

B. Lighting Systems

North Texas property owners continue to upgrade to LED lighting for energy savings and better tenant experience.

Common Systems:

• 2x2 and 2x4 LED troffers
• Linear LED pendants or surface fixtures
• Recessed downlights for lobbies and corridors
• Specialty lighting for conference rooms and amenity areas

Controls Include:

• Daylight harvesting
• Vacancy/occupancy sensors
• Networked lighting systems
• Emergency egress lighting with battery backup or generator tie-in

TI projects often require full redesign of lighting layout due to reconfigured walls and office fronts.

C. Emergency Power Systems

Emergency systems vary based on building age and code era.

Types:

• Diesel or natural gas generators
• Battery backup systems
• Transfer switches
• Emergency distribution panels

Supported Loads:

• Life safety lighting
• Fire alarm panels
• Elevators (depending on jurisdiction)
• Fire pump (if present)

Generator replacements are common when older units fail emissions requirements or cannot meet new load demands.

D. Tenant Power Distribution

Tenant build-outs often require:

• New 208/120V panels
• Dedicated circuits for breakroom appliances
• Isolated ground circuits for IT equipment
• Submetering for multi-tenant floors

Routing conduit in existing slab or ceiling cavities requires careful coordination with structural conditions.

3. PLUMBING SYSTEMS

Plumbing systems in North Texas mid-rise buildings face challenges from freeze events, water pressure variability, and aging galvanized or cast-iron piping in older properties.

A. Domestic Water Systems

Components:

• Copper water lines
• Water heaters or boilers
• Expansion tanks
• Pressure-reducing valves
• Circulation pumps

Local Considerations:

• Freeze protection for exterior or rooftop piping is essential.
• High TDS levels in some municipal water systems necessitate filtration for tenant ice machines and specialty equipment.
• Adding breakroom sinks or restrooms often requires locating near existing risers.

B. Sanitary Waste & Vent Systems

Most mid-rise buildings use cast iron or PVC piping concealed within shafts.

TI-Related Issues:

• Relocating fixtures requires slab coring and patching.
• Older cast-iron stacks may require selective replacement due to corrosion.
• Venting must comply with code based on fixture count.

C. Specialty Plumbing

Often part of more modern tenant spaces:

• Reverse osmosis systems
• Water filtration stations
• Ice machine floor sinks
• Coffee bar utility lines
• Water feature supply/drain systems

These require coordination with electrical loads and waterproofing details.

4. COORDINATION & PHASING FOR OCCUPIED BUILDINGS

Most mid-rise office MEP work occurs while tenants remain in place.

Required Practices:

• After-hours shutdowns for electrical tie-ins
• Scheduled HVAC outages
• Noise and vibration control during core drilling
• Temporary cooling solutions during equipment replacement
• Clear communication with property management and engineers

5. CODE & PERMITTING CONSIDERATIONS IN NORTH TEXAS

Each jurisdiction (Dallas, Plano, Frisco, Irving, Addison, Richardson, Fort Worth) has specific MEP expectations.

Common requirements include:

• Mechanical load calculations for TI projects
• Duct leakage testing for new distribution
• Lighting power density compliance
• Plumbing fixture count verification
• Fire damper and smoke control coordination
• Plans sealed by Texas-licensed engineers

Understanding local AHJ preferences prevents delays during inspections.