# Mechanical Analysis Blog

Posts tagged with 'HVAC'

2 Mar, 2010

## How much do ‘U-Value’ good thermal insulation? Part V

Posted by Robin Bornoff

Why is it that when you increase a cavity air gap size beyond ~30mm is there no subsequent detrimental affect on the overall U-Value? Why is it that the U-Value of the cavity gap nearly doubles when the air gap reduces to such as size so as to stagnate the air? Questions that come begging after observing the FloVENT simulation results discussed in the previous blog posting. Let’s find out…. When I … Read More

17 Feb, 2010

## How much do ‘U-Value’ good thermal insulation? Part IV

Posted by Robin Bornoff

100mm block, 50mm insulation, 50mm cavity air gap then 100mm block make up an external wall that in theory comply with a building regulation overall wall U-Value of 0.3 (W/m^2K). This got me thinking about the 50mm air gap. Why 50mm? What if it was 75mm or 10mm? Stagnant air is a great insulator, a small gap would tend to stagnate the air and might improve, reduce, the overall U-Value. A large gap would … Read More

5 Feb, 2010

## How much do ‘U-Value’ good thermal insulation? Part III

Posted by Robin Bornoff

As covered in the previous blog, air that sticks to the inside and outside walls offers a resistance to the heat that passes from the room to the inside of the wall and from the outside of the wall to the outside air. These two resistances make up part of the overall U-value, the overall ease by which heat can pass through the entire wall (or window or door etc.). The rest of the U-value is made up … Read More

2 Feb, 2010

## How much do ‘U-Value’ good thermal insulation? Part II

Posted by Robin Bornoff

It might well be that a single U-value is quoted, in reality though that single value describes the ease by which heat can pass through various stages, from an ‘inside’, passing through a ‘wall/window’ and going to the ‘outside’. The resistance (inverse of the ease, resistance = 1/ease) the heat experiences as it passes from the inside air to the inner solid surface of the wall construction (and from … Read More

29 Jan, 2010

## How much do 'U-Value' good thermal insulation? Part I

Posted by Robin Bornoff

I never trust a quoted value without having at least a little understanding as to what the value truly represents and how it was measured or derived. If you’ve ever felt inferior when someone quotes values or ranges of values at you take solace in the fact that there’s a fair chance they live on the surface of the pond of understanding and really don’t know how deep that pond is. To see a value, be … Read More

27 Jan, 2010

## Keeping the caveman warm - HVAC blog

Posted by Robin Bornoff

We knapped our first flints about 2,000,000 years ago and started to shelter from the elements in caves and simple huts about 200,000 years ago. As industries go the building industry is probably the oldest, well maybe second oldest. Our ability to both adapt to and manipulate our surroundings has set us apart from the beasts on a path of science, art and technology. Over the coming weeks, months … Read More

27 Jan, 2010

## FloVIZ, the free FloTHERM/FloVENT CFD results viewer, try it, it's free

Posted by Robin Bornoff

Computational Fluid Dynamics, CFD, is a simulation technology that provides 3D predictions of fluid flow and heat transfer for a modelled system. Be it an electronics enclosure or a building, insights into the often complex air flow patterns can help designers better understand the physical behaviour of their design. Communication of such insights helps others to appreciate the sometimes painful design … Read More

28 Jul, 2009

## A Load of HVAC TLAs

Posted by Robin Bornoff

As humans we’ve lived in ‘built environments’ for a very long time.  From the cave to the penthouse suite, the necessity to at first stay warm and dry has now evolved into the desire for comfort. The HVAC industry, rather those with the responsibility to design the built environment, have at their disposal a range of metrics used to judge comfort (comfortability? comfortness? comfortitude? comfortosity? … Read More

9 Jul, 2009

## Designing In The Box

Posted by John Wilson

As an engineer who uses CFD (Computational Fluid Dynamics) extensively I spend most of my professional life designing in the box. So, what do I mean by box? When considering the built environment a box could be a room such as an office space, building, clean room, data center, etc. For electronics cooling applications there is rack, sub-rack, pizza box,  set-top box, etc. While electronics cooling … Read More

1 Jul, 2009

## Wimbledon's Centre Court Roof

Posted by Kelly Cordell-Morris

So Murray played under the roof on Monday. It was a pretty intense match and I got absolutely nothing done that evening as I couldn’t drag my eyes away from the TV. I’ve been thinking about the design, and the fact that the humidity needs to be kept at around 50% RH to avoid condensation or the grass sweating. Humidity can effect the speed of the ball though and certainly Murray has claimed that he … Read More