Business
Pricing, margins, hiring, pay and operations for HVAC contractors, built from federal business, wage and enforcement data rather than vendor surveys.
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Office Temperature: What OSHA, ASHRAE and the Productivity Studies Actually Say
Office temperature, traced to primary sources: OSHA’s 68 to 76°F recommendation, why no US limit exists, the LBNL productivity curve, the gender evidence and what a wider setpoint…
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Local Law 97: NYC Building Emissions Limits, Penalties and a Worked Example
Local Law 97 caps emissions from New York City buildings over 25,000 sq ft. We quote the limits and coefficients from the rule, show year-one results, and work…
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Data Center PUE Statistics (2026): Industry Average, Hyperscalers and Overhead Cost
Data center PUE averaged 1.52 in Uptime Institute’s 2026 survey, or 1.36 weighted by capacity, while Google, Meta, AWS and Microsoft report 1.08 to 1.17. Plus LBNL’s US…
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HVAC Vacuum Pump: How Many Microns, How to Pull a Vacuum and the Decay Test
An HVAC vacuum pump removes air, nitrogen and moisture before a system is charged. What Carrier, Daikin, Mitsubishi and Copeland documents require, why 500 microns, the decay test,…
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Server Room Cooling: Temperature Range, BTU Sizing and the Right System
How to size and run server room cooling from primary sources: ASHRAE’s recommended inlet range, watts to Btu/h arithmetic for a 5 kW rack, system options and what…
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Building Automation System (BAS): How It Works, Who Has One, Savings and Cost
A building automation system runs a commercial building’s HVAC from one network. Our EIA CBECS tabulation shows who has one by building size, plus PNNL measured savings, BACnet,…
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Manifold Gauge: How to Read and Hook Up HVAC Gauges, and What EPA 608 Requires
A manifold gauge reads both sides of an AC system. Here is the hook-up order, a worked R-410A and R-454B reading, analog vs digital specs, and the 40…
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VAV Box: How Variable Air Volume Boxes Work, Types, Minimum Airflow and Reheat Rules
A VAV box meters air from the air handler into one zone. How pressure-independent boxes measure airflow, the box types, what PNNL and ASHRAE 90.1 say about minimum…
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HVAC Transformer: 24V Control Power, VA Sizing, Testing and Why It Blows
The 24 V control transformer explained from maker documents: what 40 VA really carries, how technicians test it, and why a transformer or board fuse that keeps blowing…
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HVAC Apprenticeship: Hours, Pay Schedules and How to Get In
How long an HVAC apprenticeship takes, what it pays, and how union and non-union routes compare, using registered program standards, 29 CFR 29.5 and BLS May 2025 wage…