Predictable Failures

HVAC Startup to Avoid Moisture and Mold Problems

The startup and shutdown sequence of a complex HVAC system is closely related to the management and control components of the HVAC system. Improper start-up sequencing of HVAC forced air systems can result in severe moisture problems.

Generally, start up a forced air HVAC systems and humid climates should consist of the following sequence of activities operation of conditioned

The operation of the conditioned make-up air systems, if applicable
The operation of all main conditioning units
The operation of the exhaust air systems.

Experience has shown that the start-up sequence often is reversed and exhaust systems become operational first.  This occurs because the exhaust system is the easiest […]

July 5th, 2016|Categories: Building Commissioning, Building Design, Building Envelope Failures, Building Failures, Design Deficiencies, Engineering, Problem Avoidance|Comments Off on HVAC Startup to Avoid Moisture and Mold Problems

Commissioning

The common practice for commissioning HVAC systems in new commercial buildings consists of verifying the following aspects of the system.

The thermodynamic performance characteristics of individual heating and cooling components
Airflows in the conditioned air distribution system and in the ventilation air system
The operating characteristics of the system management and control components.

Inherent in this process is the assumption that commissioning procedures will detect differences between the design intent and operating characteristics of the building HVAC system. A primary cause of air leakage is depressurization of the building by the HVAC system although most HVAC designs for hot humid climates at the opposite […]

Moisture Control Strategies

Understanding the patterns of moisture accumulation in buildings provides the basis for preventing moisture-related problems when commissioning a building or when analyzing the relationship between HVAC systems in the building envelope. Although mold and moisture growth staining and corrosion are the most visible signs of moisture-related damage and buildings, they are only symptoms of the fundamental problem of uncontrolled moisture flows. Thus, controlling the flow of moisture is key to preventing premature degradation of building components.

Moisture related building damage can result from any of the following events:

Intrusion of bulk moisture (i.e. rainwater and groundwater)
Moisture generated internally by human or operational activity
Moisture […]

Construction Risk Managers Should Focus on Preventing Humidity Damage

Today’s healthy construction activity is a boon for an industry that’s waited years to recover, but Florida-based Liberty Building Forensics Group® (Liberty) warns that a risk manager’s biggest nightmare could come true if steps aren’t taken to prevent moisture damage in warm, humid climates.

Construction risk management experts acknowledge water to be a leading cause of damage at construction sites.

Historically, Liberty has found humidity-based building damage to be 100 times more costly than acute water damage (pipe breaks/storms/flooding). Ironically, comprehensive water prevention strategies rarely focus on humidity issues.

“While the average water damage claim is $147,000, we routinely see humidity-related claims of […]

Risks Associated with Conducting Building Flush Out

This is the fifteenth post in a series by J. David Odom (ASHRAE), Richard Scott (AIA/NCARB/LEED AP), and George H. DuBose (CGC). It was first published as a mini-monograph for NCARB (National Council of Architectural Registration Boards).

Increased building ventilation over the design amounts can create a range of problems, such as inadequate sizing of the air filters and an inability of the air conditioning equipment to handle the increased moisture (or latent) load.

While the LEED credit mandates a 60 percent RH maximum level during this flush out period, this requirement may not be feasible with the building’s equipment. Since final […]

August 20th, 2014|Categories: Building Commissioning, Mold and Moisture|Tags: , |Comments Off on Risks Associated with Conducting Building Flush Out

Reducing the Likelihood of Mold and Moisture Problems in Building Commissioning

This is the seventh post in a series by J. David Odom (ASHRAE), Richard Scott (AIA/NCARB/LEED AP), and George H. DuBose (CGC). It was first published as a mini-monograph for NCARB (National Council of Architectural Registration Boards).

Some concepts that should be included in building commissioning to reduce the possibility of mold and moisture problems include the following:

During the design phase, a technical peer review of the document should identify issues which will likely be a major cause of moisture and mold problems in the operating building. This review may need to be accomplished by someone other than the traditional commissioning agent […]

Fundamental Commissioning (EA Prerequisite 1) and Enhanced Commissioning (EA Credit 3)

This is the sixth post in a series by J. David Odom (ASHRAE), Richard Scott (AIA/NCARB/LEED AP), and George H. DuBose (CGC). It was first published as a mini-monograph for NCARB (National Council of Architectural Registration Boards).

Intent of EA 1: Verify that the building’s energy-related systems are installed and calibrated, and perform according to the owner’s project requirements, basis of design, and construction documents.

Intent of EA 3: Begin the commissioning process early during the design process and execute additional activities after systems performance verification is completed.

Building commissioning (even the enhanced version of commissioning in LEED EA Credit 3) is not […]

Truths About Building Failures

This is the third post in a series by J. David Odom (ASHRAE), Richard Scott (AIA/NCARB/LEED AP), and George H. DuBose (CGC). It was first published as a mini-monograph for NCARB (National Council of Architectural Registration Boards).

After reviewing the designs of hundreds of new buildings over the past 20 years and observing the failures in an equal number of structures, the authors have found the following consistent truths:

Building Commissioning – The current industry approach to building commissioning (even the LEED Enhanced Commissioning version EA Credit 3) is unlikely to prevent moisture and similar building failures in almost any climate, except […]