The data that shows 14% HMO concentration

My analysis uses Bristol city council’s Pinpoint map (https://maps.bristol.gov.uk/pinpoint/):

The light blue zone is the so-called Lower Super Output Area that most closely fits Cotham Hill (LSOA references E01014558 or 022B). HMOs are depicted by house icons (Mandatory in green, Additional in blue). PBSA is in olive green; St Joseph’s is in red because it’s at the application stage.

Questions: Do the HMOs in the LSOA represent a “harmful concentration”, and if so would adding 126 PBSA beds at St Joseph’s amplify harms arising from that concentration?

Council policy DM2 says density should be assessed at “street, neighbourhood and ward levels”. Using the LSOA satisfies the “neighbourhood” test. (It is not an exact match for "the Cotham Hill area" but it's close enough.)

Density (%) = total HMOs in LSOA, divided by total dwellings x 100.

Total HMOs = 105 (Notes 1, 2, 5)

Total dwellings = 760 (Note 3, 4)

105 / 760 *100 = 13.8%

Conclusion: The concentration of HMOs in the Cotham Hill LSOA is almost 14%, which is above the 10% threshold at which council policy says “a local imbalance is likely to arise”.

Why Does This Matter?

The analysis suggests that a “harmful concentration” of HMOs exists—but St Joseph’s is not an HMO, so why is the HMO concentration a concern? 

It is significant because council policy requires planners to gauge how different kinds of housing—or, by extension, the likely activities of their occupants—will interact with each other.

Policy DM2 says a development will not be permitted if it “would create or contribute to a harmful concentration of such uses within a locality as a result of any of the following: Exacerbating existing harmful conditions ... .“ The phrase “such uses” refers to a list of housing types, including HMOs and PBSA. Elsewhere, DM2 also makes clear that one of the ways one kind of housing can affect others is via “levels of activity”, which is clearly a reference to the activities of occupants. (Note 6, 7)

So, if it is established that the existing HMO-based student accommodation in Cotham Hill constitutes a “harmful concentration” associated with harms such as noise and waste, the question then becomes whether the St Joseph’s proposal is likely to add to those harms.

From the map, it is clear that St Joseph’s does not sit within the visible cluster of HMOs, but as a large development, it would have a sphere of influence. (Note 8) Whenever its occupants go outside the site, they are likely to be walking through areas that already have a heavy night-time foot traffic because of the sizable student population in HMOs.

The noise generated late at night by groups of students walking along residential streets on their way to and from pubs, clubs, and house parties is one of the chief complaints by longer-term residents. Given that the future occupants of St Joseph’s would also be students, and therefore likely to exhibit some of the same behaviours, there is a clear risk they would contribute to these “harmful conditions”, as described by DM2.

Planning officers have so far rejected these inferences. Whether their comments change in the new report submitted to the October meeting will be a key issue to look out for.

Notes:

(1) hand-counted, because the public version of Pinpoint can’t generate a tally automatically. (Count with care: One HMO icon can obscure another, and some icons represent more than one HMO. Zoom in. Turn off the LSOA boundary temporarily to click HMO icons.)

(2) the 105 total is likely to be an under-count. Some HMOs are not shown. They are temporarily removed from the map while awaiting licence renewal (usually once every 5 years). HMOs operating illegally without a licence don’t appear. Nor do properties that have planning approval as HMOs but are not currently in use as such. (The council has that data and includes it when calculating density for planning purposes.)

(3) “dwellings” = all residential property, including houses, flats and the HMOs themselves. Data from gov.uk webpage https://www.gov.uk/government/statistics/council-tax-stock-of-properties-2026?utm_source=chatgpt.com. Download file “CTSOP1.1: number of properties by Council Tax band, local authority and lower and middle super output area at 31 March 2026”. On opening, go to line 37363 of the spreadsheet, or search for “E01014558”. Read the total (760) at far right.

(4) Other LSOA data has a number for “households”, but this measures something different than dwellings, even though the numbers are fairly similar.

(5) We don’t know how many of the HMOs are occupied by students. There is strong anecdotal evidence that, in Cotham Hill, the vast majority are. We can also cross-check with other data. But actually, it doesn’t matter. Policy DM2 is not concerned about who is occupying HMOs—whoever they are, they are usually short-term residents. It is therefore not necessary to identify all occupants for the purposes of calculating HMO density or drawing any other conclusions.

(6) Planners seem to have struggled with this concept. They have repeatedly said they can only consider impacts generated from the St Joseph’s site itself (that is, from within the building or its garden). But it is clear that DM2 does not take such a restrictive view.

(7) “Emerging” Policy H7 also stipulates that: “In all cases [when assessing PBSA applications] the proximity and concentration of houses in multiple occupation should also be taken into account.” This makes explicit what is already implicit in policy DM2.

(8) The sphere of influence is recognised in “emerging” policy H7, which suggests that PBSA applications should be evaluated by looking at what other PBSA developments, if any, might already exist within 200 metres of the site. This is double the 100-metre guideline used in evaluating HMO applications. This makes sense: an HMO is a house, and surveying properties using a 100m-radius circle will take in several adjoining streets. In HMO policy, this satisfies DM2’s “neighbourhood” test, but it cannot do the same in the case of a large site like St Joseph’s.

There was a bizarre moment in the September committee meeting when a planner drew a 100m-radius circle from the centre of St Joseph’s and said the circle contained only a handful of HMOs, so there was no evidence of concentration. (The St Joseph’s site itself filled much of the circle.) Applying an HMO rule to a PBSA site was not justified by planning policy or logic. A sensible assessment would have been to survey properties within 200 metres of the site, as specified in Policy H7. This would have identified many more HMOs.

An even more holistic approach, better fitted to policy DM2, would have been to ask whether the expected activity of 126 students based at St Joseph’s would be likely to amplify the impact of the neighbouring HMO student population.