BER rating calculation

[Roro999]

I recently checked my BER rating report and I feel the floor area understates the actual if I measure outside length by breath x 2 (2 storey). BER says floor area is 85 sq metres whereas my calculation is 100 sq metres.
Could BER be mistaken and if advertising for sale I would rather have it stated as 100 sq m as price I would realise would be greater.

 

[jpd]

Why don't you ask whoever did the BER for an explanation?

 

[ClubMan]

if I measure outside length by breath x 2 (2 storey)

BER uses internal floor area although a difference of 15sqm between that and external seems unusual.

Understand BER Ratings | Home Energy | SEAI

A Building Energy Rating (BER) certificate rates the energy performance of your home. Learn what the rating means for your home's energy efficiency and how it is calculated.

www.seai.ie

if advertising for sale I would rather have it stated as 100 sq m as price I would realise would be greater.

Aren't floor area and floor plans normally specified separately from the BER on a sale listing?

Why don't you ask whoever did the BER for an explanation?

This makes most sense alright.

 

[_OkGo_]

The methodology is all on the SEAI website. They measure according to DEAP guidelines which you can find here

DEAP Software & Methodology | Support for BER Assessors | SEAI

DEAP is used by BER assessors to calculate the energy performance and carbon dioxide emissions of a home's space heating, water heating, ventilation and lighting.

www.seai.ie

But it should be fairly obvious why you have an error. You are measuring external walls, floor area is based on internal wall.

You have a 2 storey with 50sqm per floor. If it was a perfect square, it would be 7.07 x 7.07. Your external walls will be at least 0.3-0.35m so now you are at 6.72 x 6.72

For 85sqm or 42.5sqm per floor, your internal walls would be 6.52 x 6.52. So there is only a difference of 0.2m in the length/width measurement.

Maybe your assessor measured slightly on the small side but you more than likely measured on the big side even with the external walls. Go back and measure the internal width/breadth and you will probably land on a very similar number to the 85sqm

 

[Leo]

if advertising for sale I would rather have it stated as 100 sq m as price I would realise would be greater.

No, the footprint occupied by the house is not the floor area. The area of the overall footprint taken up by the walls, fireplaces, or other fixtures is excluded from the floor area. Walls are not floors. Note the BER methodology is not designed to get to 100% accuracy on many aspects, including floor area.

 

[Roro999]

Thanks for the help.