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Latest Blogs
Plumbing Estimating Software for Faster, Accurate Tenders
How to turn a partial floor plan into an accurate bid before the deadline hits.
Plumbing Fixture Units, Explained: Charts for Every Code
Supply, Drainage, and a Chart for Every Major Code
RIBA Plan of Work Stages: How They Shape Construction Projects
Every RIBA stage exists to answer a specific question at the optimal time to prevent project delays or extra costs.
Latest Charts
Plumbing Fixture Units, Explained: Charts for Every Code
Supply, Drainage, and a Chart for Every Major Code
How to Read a Psychrometric Chart (Without Losing Your Mind)
This psychrometric chart guide breaks down every property, process, and worked example in plain English.
Ductulator Chart: Practical Guide for Mechanical Engineers (Free Download)
Duct size directly affects noise, energy, and layout, which is why you should use the Ductulator Chart to get it right.
Latest Formulas
How to Calculate Air Changes Per Hour
Learn the ACH formula, how to calculate air changes per hour from airflow and room volume, and typical values by room type.
CFM Calculation Formula: 4 Ways to Calculate Required Airflow
Four CFM calculation formulas for ventilation, cooling load, and duct sizing, with a fully worked example.
Friction Factor: The Small Coefficient Driving Pressure Drop
If you want to size a pipe or duct accurately, you must calculate the friction factor: a technical, iterative process with multiple variables (Re, material, diameter, temperature). This guide explains the methods and shows you how to apply them, so your pressure drop calculations are always precise.
Latest Spreadsheets
FREE Pipe Volume Spreadsheet
Access h2x’s free pipe volume spreadsheet to streamline calculations, optimise design, and enhance efficiency in piping projects.
h2x vs. Spreadsheets
Since its launch back in 1985, Microsoft’s spreadsheet application Excel has gone on to become accepted as the leading program for the management and calculation of data.
Hardy Cross Method – Sizing a Ring Main (FREE Spreadsheet)
Flow rate and friction loss in a pipe network system can be difficult to calculate. When the pipe network is in a ring main (also known as a closed-loop) formation, the calculations are extra difficult.
This difficult calculation is very common for fire hydrant ring main size designs and the ring main design calculations.
Latest Calculators
FREE Water Flow Rate Calculator
Water Flow Rate Calculator Use this free Water Flow Rate Calculator to estimate flow rates from plumbing fixtures…
FREE Heat Loss Calculator
Heat Loss Calculator Use the Heat Loss Calculator to calculate heat loss in any room or building by…
FREE Ductulator
Ductulator Use our free online Ductulator to calculate velocity, pressure drop, Reynolds number, and friction factor based on…
Resources
Plumbing Estimating Software for Faster, Accurate Tenders
How to turn a partial floor plan into an accurate bid before the deadline hits.
Plumbing Fixture Units, Explained: Charts for Every Code
Supply, Drainage, and a Chart for Every Major Code
RIBA Plan of Work Stages: How They Shape Construction Projects
Every RIBA stage exists to answer a specific question at the optimal time to prevent project delays or extra costs.
What Is Thermal Lag? Understanding Time Lag and Thermal Mass in HVAC Design
Why heat arrives hours after the temperature peaks, and what that means for cooling loads, plant sizing, and comfort.
Designing to BS EN 12831-1:2017 in h2x: A Step-by-Step Guide
A practical guide to configuring BS EN 12831-1:2017 heat loss calculations, ventilation inputs, and system settings in h2x.
Commercial Plumbing Design Software: Five Takeaways for MEP Engineers
Review insights from a recent h2x live session on designing domestic water systems.
Best MEP Software in 2026: 10 Tools Compared
Compare the leading MEP design, calculation and BIM platforms to find the right software for your engineering workflow.
Beat The MEP Software Learning Curve
Learn how to choose, introduce and support an MEP design platform your engineering team will actually use.
ASHRAE 183: The Industry Standard for HVAC Load Calculations
Learn what ASHRAE Standard 183 requires for HVAC load calculations and what engineering design software needs to produce compliant, audit-ready results.
Do Heat Pumps Work in Cold Weather? How They Extract Heat From Air Below 0°F
Yes, heat pumps can work below 0°F (-18°C). Here’s how cold-climate systems extract heat, maintain capacity, and handle defrost cycles.
CFM Calculation Formula: 4 Ways to Calculate Required Airflow
Four CFM calculation formulas for ventilation, cooling load, and duct sizing, with a fully worked example.
HVAC System Selection for Any Building Size
A practical guide for mechanical engineers on when and why to specify each HVAC system selection type.