Daylight in Extra-Care Housing: Enhancing Occupants’ Sight and Health Dr Alan Lewis University of Manchester

Serious sight loss (i.e. registrable) affects approximately: 1 in 8 of people aged over 75 1 in 3 of people aged over 90 (Thomas Pocklington Trust, 2006) The demand for specialist housing By 2026 there will 2.4 million more older households (CLG, 2008) Between 2004 and 2010 the UK government provided £227 million total capital funding for the Department of Health’s Extra Care Housing Fund Initiative (Darton + Callaghan, 2009) The Coalition Government has pledged £300m for the development of specialised housing (including extra-care) (Department of Health 2012)

Aims of the current study: to identify barriers to compliance with current guidance on daylighting to develop strategies for the circumvention of these barriers Methodology Secondary analysis of EVOLVE study data Semi-structured interviews with 20 architects/housing providers Workshops with architects and housing providers

Benefits of daylight as task lighting Generally gives higher illuminances than electric light Reduces contrast between task and background Provides good colour rendering Health benefits of visible daylight Helps the body to regulate production of melatonin Helps to regulate sleep patterns Stimulates the body’s production of serotonin Reduces symptoms of depression Views of the outside world Provides link to nature and information about weather Helps to prevent feelings of isolation

Criteria for good daylighting A 24-hour cycle of illumination that includes periods of darkness and bright light Exposure to bright daylight in winter months Satisfied if there is an average daylight factor of at least 2% in one habitable room… …or there is a habitable room that receives direct sunlight for one half-hour per day between 1 November - 31 January The need of building users for a sense of contact with the outside world Avoidance of glare that causes discomfort or reduces visibility of hazards (Source: Tregenza and Wilson, 2011)

Rooms with natural light Hall = 8% Lounge = 100% Kitchen = 45% Bedroom = 100% Bathroom = 9% Percentage of dual aspect dwellings = 35%

Interview responses: building layout Building layout affected by the need to make a housing scheme financially viable, in terms of: cost of construction the need to fit the maximum number of units on a site “...if I can get forty two I'll have that... and the minute you draw forty three you can't ever go back, it's forty three or nothing.” [Architect #2] Sale value of living units can affect how much money is available for communal facilities, etc. “...if you gain more sales values for certain sites, you can then have slightly larger communal areas. [In one scheme], for instance, we got large full air conditioned atria...” [Architect #8]

Recommended minimum average daylight factor in dwellings Lounge = 1.5% Kitchen = 2% Bedroom = 1% (Source: British Standards Institute, 2008) One habitable room = 2%, all other habitable rooms 1% (Source: Tregenza and Wilson, 2011)

Average Daylight Factor: Lounge

Average Daylight Factor: Kitchen

Average Daylight Factor: Bedroom

Big windows, no over-hanging eaves or balconies

Interview responses: evaluating daylight at the design stage Few architects undertake daylight factor calculations Where it is necessary to undertake df calculations (e.g. To comply with Code for Sustainable Homes), external consultants are generally used Window size rarely reduced to avoid excessive heat loss......but solar gain can be an issue...and energy rating takes priority over daylighting Window size rarely reduced to cut costs Occasionally window size restricted by planning considerations

Sunlight Percentage of lounge windows with: - sunlight AM or PM = 87% - sunlight AM and PM = 26% - no obstruction = 51% - shading devices = 50% Interview responses: Many units single aspect Deck access favoured by some interviewees, but considered too expensive or too risky by others

Aspect Percentage of lounge windows with view of: - natural features = 81% - human activity = 77% - near + far features = 44% Interview responses: Site constraints an issue It is usually possible to create views of gardens and courtyards Often difficult to give depth to a view

So how can good daylight standards be achieved in extra-care housing?

Average Daylight Factor D = T M A w Θ A(1 – R 2 ) T is the glazing transmittance A w is the net glazed area (m 2 ) Θ is the angle subtended by the visible sky A is the total area of the walls, floor and ceiling (m 2 ) R is the area-weighted average reflectance of the interior surfaces Assumes an overcast sky

Average Daylight Factor = 0.3%

Average Daylight Factor = 0.4%

Average Daylight Factor = 1.6%

Average Daylight Factor = 3.8%

Θ Θ = greater than 65° conventional window design will provide good daylight Θ = 45° – 65° larger windows or changes to room layout usually required Θ = 25° – 45° very difficult to provide adequate daylight unless very large windows used Θ = less than 25° often impossible to achieve reasonable daylight Visible Sky Angle

Impact of window size on view

Conclusions and recommendations Ultimately cost determines what is possible Daylight levels could be increased through Use of rule-of-thumb techniques for estimating daylight levels Provision of larger windows and avoidance of large overhangs – but note the risk of solar gain In the long term, computer modelling of sunlight and daylight might be more feasible than at present