Windows | Door | Building Science / Envelope and More

Where does Energy Star come from? The Environmental Protection Agency (EPA) administers this government backed rating system that gives consumers an unbiased standard to go off when purchasing products for a home or building. The energy star label is different than the NFRC sticker . Windows are just one of the many products within a home that you can find energy star labels for. The new criteria (version 7.0) for energy star windows and doors represents an improvement of thermal performance. Which means lower u-values and slightly lower SHGC. This new version goes into effect on OCTOBER 23, 2023. This means that window manufactures will need to specify which windows qualify and which do not qualify to the new standard starting on October 23rd. Most are familiar with the term “energy star windows” - but what does that really mean? The US is split into four climate zones: Northern, North-Central, South-Central, and Southern (See map below). Each zone has different u-factor and Solar...

What do I mean by “new construction” and “replacement” windows? The way most people understand the difference between the two is that new construction windows utilize a nailing flange (fin that protrudes out from the window frame surrounding entire perimeter of the window) to install the windows and replacement windows have NO nailing flange. This over simplification of these terms often leads to buying the wrong product and poor installations. However, for the sake of mutual understanding, when I use those terms assume that is what I mean.  Nailing Flange Around Window Frame 1st Myth: When replacing windows, always use "replacement windows" - aka no nailing flange. It’s actually almost the exact opposite. Replacement windows should almost always HAVE a flange for installation.  The only times I would deem it acceptable to replace a window withOUT a flange is twofold: 1. Your house was build pre 1945 and you have the old sash weight wood double hung windows. For installing ne...

  If you are familiar with construction, then you may know that measuring and ordering windows can be complicated. Whether they’re for a new construction house or a replacement project, it’s crucial to know the difference between “RO” sizing and “net” sizing.   Rough opening (RO) size is simply the framed opening size. Meaning after a window is framed by the framer, the width and height of the stud to stud measurement is the RO dimension. Net size (also called frame size or heel size) is the actual width and height of the window from outside edge to outside edge. New Construction: If you’re building a new house then windows are always part of the equation. Looking at blueprints it may seem obvious what the sizes are - especially if there is a window schedule. However, there can be some confusion about what the ACTUAL size of the windows will come.  The important thing to know is that all specs related to window sizing on house plans is always the RO size.   2850 = 2'...

Thermal Bridge vs  Thermal Break If you’re new to building science these terms may seem esoteric but hopefully you will come to a better understanding of them after reading this.  Think of the term thermal as HEAT .  Think of term bridge   (in thermal bridge) as a connection between point A and point B - which is what an actual bridge is. So thermal bridge is simply the act of heat transporting through or on the “bridge” from point A to point B. Think of the word break (in thermal break) as in shutting down a lane of traffic on that “bridge.” Now it’s a one lane road, cars are going much slower and there is a greatly reduced number of vehicles crossing. During peak hours more cars might travel through then other times of the day. But nonetheless there has been a great interruption. In terms of heat transfer (or thermal bridge), once a thermal break is incorporated, heat (and cold) has a much harder time traveling from point A to point B.  Heat/...

CLAD WINDOWS Clad windows simply refers to the different materials “capping” the wood window so that it becomes more durable and less likely to rot. Many window manufactures design a wood interior, clad exterior window. Often times there are interior wood specie options as well  as different exterior cladding choices such as vinyl, fiberglass and aluminum. I will be focusing on an aluminum clad exterior in this post. There are a number of aluminum clad wood windows on the market and they are not all created equally.  When comparing various manufacturers to one another, it is important to understand the differences in materials and construction that windows are made out of.  The aluminum exterior is made in one of two ways: roll form or extruded. HOW THEY ARE MADE ROLL FORM The roll forming process uses a pair of rolls to fabricate the metal. Metal sheets are passed through the rolls several times until the desired shape or profile is achieved. EXTRUDED The extruded alumin...