Hea01 Daylighting

(2 credits)

Aim

To ensure residents have access to good levels of daylight, via windows and/or skylights.

Question

What is the glazed area as a percentage of the room floor area?

Credits	Answer	Select a single answer
0	A	Question not answered
1	B	All relevant rooms meet the requirements for 1 credit at their latitude
2	C	All relevant rooms meet the requirements for 2 credits at their latitude

Assessment criteria

Criterion	Assessment criteria	Applicable answer
1	Relevant rooms are those where residents will spend a significant amount of time while awake. These include:  Living rooms, dining rooms and studies  Eat in kitchens	B,C
2	All relevant rooms must meet the requirements in Table 13.	B,C
3	Calculations to demonstrate compliance are not required for every room. The worst-case scenario can be used to demonstrate the minimum level of performance, with all other room window combinations assumed to score above this.	B,C

Methodology

Calculating glazed area as a percentage of occupied room area and assessment against the minimum performance requirements

The following steps must be followed in order to assess whether the asset demonstrates compliance with the minimum performance requirements. 

1. Determine the latitude for the asset’s location. 
2. Calculate the net internal area (m2 ) for each relevant room. 
3. For each relevant room, calculate the total glazed area (m2 ) of all windows and rooflights within the space. The frames are not included in the calculation, only the area of glass. 
4. For each room, calculate the percentage of glazed area to room area as follows: 𝑷𝒆𝒓𝒄𝒆𝒏𝒕𝒂𝒈𝒆 𝒈𝒍𝒂𝒛𝒆𝒅 𝒂𝒓𝒆𝒂 𝒕𝒐 𝒇𝒍𝒐𝒐𝒓 𝒂𝒓𝒆𝒂 = ( 𝑻𝒐𝒕𝒂𝒍 𝒈𝒍𝒂𝒛𝒆𝒅 𝒂𝒓𝒆𝒂 𝒊𝒏 𝒓𝒐𝒐𝒎 𝑵𝒆𝒕 𝒊𝒏𝒕𝒆𝒓𝒏𝒂𝒍 𝒂𝒓𝒆𝒂 𝒐𝒇 𝒓𝒐𝒐𝒎) × 𝟏𝟎𝟎 
5. For each room, check if there are any external obstructions (e.g. adjacent buildings or structures, trees or hedges, etc.) that will potentially limit the amount of daylight reaching the room. If there is an obstruction, its distance away from the glazing must be greater than its height above the centre of the glazing. For example, if an obstruction’s height is 10 metres above the centre of the glazing, then the obstruction must be at least 10 metres away from the glazing. Where an obstruction does not meet this distance requirement, it is not possible for the room in question to comply with the minimum performance requirements. 
6. For each relevant room, compare the glazed area to room area percentage to the minimum performance requirements in Table 13 for the asset’s latitude to assess whether the room is compliant or not.

Checklists and Tables

Table 13: Minimum performance requirements for glazed area as a percentage of occupied room area

Evidence

Criteria	Evidence requirement
-	The evidence below is not exhaustive, please also refer to the ‘BREEAM evidential requirements’ section in the scope of the Guidance for appropriate evidence types which can be used to demonstrate compliance.
1-3	Documentation specifying the occupied room area and glazed area and calculations in accordance with the Methodology.
1-4	Photographs of building elevations, glazed areas in occupied space and any obstructions.

Additional information

Glazed areas and overheating

This assessment issue focuses on the provision of minimum glazed areas for the purposes of allowing good levels of daylight within occupied space. As such, no maximum limit has been stipulated. However, overheating in a space can be a problem if glazed areas are too large.

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