How often do hotel guests complain that their room is “dark”? The HotelBank Editorial Team counted it with NLP analysis of guest reviews. We split mentions of room brightness, natural light and lighting in the past 24 months of reviews into negative and positive, and took the top 100 hotels on each side by number of mentions. The negative side had 6,017 mentions in total, 3.3 times the 1,829 on the positive side. Sixty of the negative-side hotels are in four prefectures (Tokyo, Kyoto, Osaka and Fukuoka), and most of them are limited-service hotels in cities. This article looks at the locations, hotel types and sizes where “too dark” complaints show up most, the gap in estimated settled ADR within the same municipality and hotel type, the cost per room of lighting, interior and window upgrades, and, checked against the legal texts, why daylight affects room rates in office-to-hotel conversions.

“Dark” Comments Outnumber “Bright” 3.3 to 1: Comparing the Top 100 on Each Side

Start with the overall volume. The top 100 negative-side hotels had 6,017 mentions and the top 100 positive-side hotels had 1,829, a ratio of 3.3 times. The median mention rate per property also differed widely: 3.38% on the negative side and 0.84% on the positive side. On the negative side, roughly one review in 30 refers to the room being dark.

The two groups, however, have different review bases. The 100 negative-side hotels had 196,429 reviews in total and the 100 positive-side hotels had 278,845, so the positive side is made up of hotels with more reviews. Measured against total reviews, mentions account for 3.06% on the negative side and 0.66% on the positive side, and the gap actually widens to 4.7 times. Room brightness appears to be something guests rarely comment on when it is good, but often write about when a room feels dark.

Source: HotelBank Editorial Team research (NLP analysis of guest reviews, past 24 months)

60 Negative-Side Hotels in Tokyo, Kyoto, Osaka and Fukuoka: Mostly Urban Limited-Service Hotels

By prefecture, the 100 negative-side hotels break down as Tokyo 22, Kyoto 18, Osaka 10 and Fukuoka 10, so these four prefectures alone account for 60. Big cities also lead on the positive side, but the spread is wider (Osaka 17, Tokyo 15, Kyoto 10, Aichi 7) and Fukuoka has only 3. Kyoto, with 18 hotels on the negative side against 10 on the positive side, was one of the areas with the largest gap.

Source: HotelBank Editorial Team research (NLP analysis of guest reviews, past 24 months)

By hotel type, the negative side has 61 business hotels and 24 city hotels, so limited-service hotels make up 60%. There were only 6 resort hotels and 3 ryokan. The positive side has a similar mix, with 62 business hotels and 29 city hotels. This suggests that what separates the two groups is not the hotel type itself but how room specifications differ within the same type.

Source: HotelBank Editorial Team research (NLP analysis of guest reviews, past 24 months)

At the municipal level the concentration is even clearer. The most negative-side hotels are in Shimogyo Ward, Kyoto (14), followed by Hakata Ward, Fukuoka (6) and Shinjuku, Tokyo (5). Shimogyo also has 6 hotels on the positive side, so opinion is split within the same ward. The map shows, as circles, the municipalities with at least 2 hotels on either side (each circle is placed at the average coordinates of hotels in that municipality, not at individual hotel locations).

Source: HotelBank Editorial Team research (NLP analysis of guest reviews), MetroEngines Research & Consulting. Circle size = number of hotels. Blue = negative side, light blue = positive side

Over 80% on Both Sides Sit in Commercial Zones: Buildings and Rooms Matter More Than Location

Since the hotels are concentrated in cities, one might suspect that a location in a dense commercial zone is itself the cause of dark rooms. We therefore overlaid each property’s address on the zoning data in the Ministry of Land, Infrastructure, Transport and Tourism (MLIT) Real Estate Information Library. The number of hotels in commercial zones was almost the same on both sides: 84 negative and 85 positive. Looking only at districts with a floor area ratio of 800% or more, the negative side had 37 of the 85 hotels whose zoning could be confirmed (44%), and the positive side had 30 of 95 (32%). The negative side is somewhat more common in high-density districts.

Even so, it matters that hotels described as “bright” and hotels described as “dark” stand side by side in the same commercial zones. Site conditions such as distance to neighbouring buildings and window orientation cannot be changed, but the lighting plan, interior colours and window treatments are specifications that a renovation can address. For hotels that attract “dark room” comments, this can be read as room for rate growth.

Source: Prepared by MetroEngines Research & Consulting from the MLIT Real Estate Information Library (zoning)

Room Count and Opening Year: Newer Hotels Also Get “Dark” Complaints

Comparing hotel size, the largest group on the negative side is 100 to 199 rooms (31 hotels), and 20 have 99 rooms or fewer. The positive side leans toward large hotels, with 38 having 300 rooms or more. Because the top 100 are chosen by number of mentions, large hotels with many reviews are more likely to be included, and this selection effect also contributes to the positive side’s tilt toward large hotels.

Source: MetroEngines Research & Consulting; HotelBank Editorial Team research (NLP analysis of guest reviews)

By opening year (the year the property began operating in its current type; for hotels opened by converting an existing building, the year of the conversion), the negative side has 33 hotels opened in 2020 or later, more than the 29 opened in 1999 or earlier. On the positive side, 48 opened in 2020 or later and 18 in 1999 or earlier. Newer hotels are more likely to be described as bright, but many hotels opened in the 2020s still draw a lot of “dark” comments. Designs that fit as many rooms as possible onto narrow plots, and interiors finished in calm dark colours, may look appealing in photos but can strike guests as dark.

Source: MetroEngines Research & Consulting; HotelBank Editorial Team research (NLP analysis of guest reviews)

How Estimated Settled ADR Differs Within the Same Municipality and Hotel Type

Is the brightness rating linked to room rates? For each hotel on both sides, we compared its estimated settled ADR for the 12 months from November 2025 to October 2026, month by month, with the median for the same municipality and hotel type (the median number of comparison properties per month was 42), and averaged the ratios. The result is an index with the median set to 100. It covers only the validated hotel types (business, city, resort, ryokan) and excludes the 11 hotels that appear in both top-100 lists.

Source: MetroEngines Research & Consulting (negative side N=78, positive side N=74); HotelBank Editorial Team research (NLP analysis of guest reviews)

The median index was 106 on the negative side and 134 on the positive side. Both groups consist of popular hotels with many reviews, so both are above the area median. But the premium is 28 points larger on the positive side. By hotel type, business hotels (N=54 each) scored 116 on the negative side and 136 on the positive side, and city hotels (N=17 each) scored 99 and 113, so the gap points in the same direction for both types.

Note that this gap is not entirely due to room brightness. The positive side includes more new and large hotels, and other factors such as brand strength, views and room size also affect rates. In fact, there was almost no correlation between mention rate and index among the 78 negative-side hotels (correlation coefficient −0.08). The index was 125 for the third with the lowest mention rates (0.50% to 2.51%, 26 hotels), 102 for the middle third (2.54% to 5.52%) and 105 for the top third (5.63% or more), so it is not a simple case of rates rising as mention rates fall. Still, the fact that hotels described as bright achieve higher rates within the same area and hotel type is a useful pointer when considering a renovation.

Source: MetroEngines Research & Consulting; HotelBank Editorial Team research (NLP analysis of guest reviews). Horizontal axis on a log scale. Individual hotel names are not shown

Hotels Described as “Bright”: High Mention Rates Among Small Independents Too

The positive-side top 100 also includes independent properties with few rooms. By mention rate, the ryokan Kaiseki Ryoan Ashikari (懐石旅庵 阿しか里) in Yugawara, Kanagawa (19 rooms) has the highest rate on the positive side at 4.53%, with reviews such as “bright, with the warmth of wood” and “a very bright, open room.” Sakaide Plaza Hotel (坂出プラザホテル) in Sakaide, Kagawa (50 rooms) is also high at 2.92%, where guests mention the room brightness together with “nicely renovated rooms.”

Source: HotelBank Editorial Team research (NLP analysis of guest reviews, past 24 months, counted on November 2, 2026). Independent properties selected from the positive-side top 100. Review quotes are partial and translated

What these properties have in common is that brightness is remembered as part of the room itself: how natural light enters, wooden interiors, or the clean white of a recent renovation. Brightness is not a single piece of equipment but an experience created by the combination of interior, lighting and window treatments.

Cost per Room by Renovation Item: Lighting, Interior Brightness and Windows

Next, we build up the cost per room of renovations that address “dark room” comments, using published unit prices. The unit prices are figures published by contractors as closed-deal data or market guides, and the quantities are per-room assumptions (6 downlights, 2 indirect-lighting fixtures plus 1 new outlet, 50㎡ of wall and ceiling wallpaper, and 1 window). The quantities vary widely with room size and existing equipment, so results are shown as ranges. For older properties that also renovate interiors, how much a pre-works survey adds to the cost is estimated in 64.5% of Japan’s Hotel Rooms Predate 2006 — Asbestos Adds Up to 25.8%.

*1 Meetsmore, “How to replace LED downlights and typical costs” (closed-deal data for January–December 2024, updated May 28, 2025) / *2 Crowdsourcing Times, “Typical costs of electrical work” (updated January 3, 2025) / *3 CREX, “Typical costs of wallpaper work” (updated February 4, 2026) / *4 Wilico, “Typical costs of curtains” (updated March 28, 2026) / *5 Tenpo Naiso.com (BPB Consulting Co., Ltd.), “Hotel and ryokan interiors” (updated October 15, 2026; guideline for properties with 30+ rooms). All are general consumer guidelines published by contractors or price-comparison sites, and do not include the costs of bulk hotel orders, night work, or taking rooms out of sale.

Source: Prepared by MetroEngines Research & Consulting by multiplying the published unit prices in notes *1 to *5 above by assumed quantities per room. Indirect lighting and the four-item total show the lower bound only, as only a minimum unit price is published

There is also a timing issue for lighting upgrades. Under the Minamata Convention on Mercury, the manufacture, import and export of fluorescent lamps for general lighting are being phased out: compact types from January 1, 2027, and straight-tube and circular types from January 1, 2028 (Ministry of the Environment). Using or selling existing stock is not banned, but before replacement lamps become harder to source, this is a good opportunity to switch guest-room lighting to LED and review colour temperature and dimming at the same time.

How Much ADR Must Rise to Pay Back the Cost? An Estimate for Business Hotels

To estimate how many years it takes to recover renovation costs through higher rates, we used the median estimated settled ADR of the negative-side business hotels (N=54), ¥15,100, and the business hotel room occupancy rate of 75.3% (January–December 2025, nationwide) from the Japan Tourism Agency’s Overnight Travel Statistics Survey, final figures for 2025. Annual room revenue per room comes to about ¥4.16 million, so each 1% rise in ADR adds ¥42,000 a year. We assumed occupancy stays the same before and after the renovation and applied the extra revenue, before commissions and other deductions, directly to the payback period.

Source: Estimated from MetroEngines Research & Consulting (estimated settled ADR, November 2025 – October 2026) and the Japan Tourism Agency’s Overnight Travel Statistics Survey (2025 annual figures, final, published July 6, 2026)

The ADR increases are assumptions; there is no data showing how much a brightness upgrade alone would raise rates. But compared with the index gap within the same area and hotel type seen earlier (116 on the negative side vs 136 on the positive side for business hotels), +1% to 5% is a fairly conservative assumption. A combined lighting, interior and window upgrade pays back in under three years even with a 1% rate improvement, making it an easier option to consider before a full renovation for hotels that attract “dark room” comments. For a full interior refit, on the other hand, the deciding question will be whether an improvement of 3% or more is achievable. A real-world example of per-room investment at close to full-renovation scale is covered in Hotel Urashima’s ¥4bn renovation (¥10.96 million per room).

Why Daylight Affects Rates in Office-to-Hotel Conversions: What the Building Standards Act and Hotel Business Act Say

When an office building is converted into a hotel, the treatment of daylight shapes how much freedom the plan has. Article 28, Paragraph 1 of the Building Standards Act requires habitable rooms in residences, schools, hospitals, clinics, dormitories, boarding houses and similar buildings to have openings for daylight of at least a ratio set by Cabinet Order, within a range of one-fifth to one-tenth of the floor area. The rooms covered are specified in Article 19 of the Order for Enforcement of the Act, which sets one-seventh or more for “bedrooms in dormitories or guest rooms in boarding houses,” but hotel and ryokan guest rooms are not listed. Window-area requirements are therefore looser than for conversion to housing, which is one reason office-to-hotel conversions are a popular choice. For a real example of re-dividing an existing building into guest rooms, see the conversion of Citadines North Shinjuku Tokyo into 179 units.

That does not mean there are no requirements. Paragraph 2 of the same article requires every habitable room, regardless of use, to have openings for ventilation of at least one-twentieth of the floor area or ventilation equipment meeting Cabinet Order standards. Article 1, Paragraph 1, Item 3 of the Order for Enforcement of the Hotel Business Act also requires ryokan and hotel facilities to have “adequate ventilation, daylight, lighting, damp-proofing and drainage facilities,” with the details filled in by the ordinances and practices of prefectures and cities that operate public health centres. In addition, Article 35-3 of the Building Standards Act requires that habitable rooms without the openings specified by Cabinet Order have main structural parts of fire-resistant construction or non-combustible materials. Plans for guest rooms with few windows therefore presuppose fire-safety measures and prior consultation with the competent public health centre.

Even if the law allows flexibility on windows, guests judge by a different standard. In our data, “dark” and “bright” comments split within the same commercial zones, and rate levels differed within the same area and hotel type. When dividing a deep office floor plate into guest rooms, the key question for post-conversion rates is whether to raise the experience of the rooms without windows through lighting design and interior brightness, or to separate room types and price them differently, rather than selling window-facing and interior rooms with the same specification at the same rate.

Summary: “Dark Room” Comments Point to Specifications You Can Change

Guests rarely comment on room brightness when it is good, but often write about it when a room feels dark. The 6,017 mentions at the top 100 negative-side hotels were 3.3 times those on the positive side, and they were concentrated in limited-service hotels in the cities of Tokyo, Kyoto, Osaka and Fukuoka. Over 80% of hotels on both sides are in commercial zones, which suggests that what separates them is the building and room specification rather than the location. Within the same municipality and hotel type, hotels described as bright had an estimated settled ADR premium 28 points larger.

Combining LED lighting, lighter-coloured wallpaper and new window treatments costs from about ¥110,000 per room based on published unit prices, and pays back in under three years if ADR improves by 1%. With the upcoming ban on fluorescent lamp manufacture setting the timing for lighting upgrades, rooms that attract “dark” comments are worth revisiting as room for rate growth. In office conversion projects, too, it pays to build the brightness guests actually perceive into room types and pricing, separately from the legal window requirements.

Related Articles

• 64.5% of Japan’s Hotel Rooms Predate 2006 — Asbestos Adds Up to 25.8%
• Hotel Urashima’s ¥4bn Renovation: ¥10.96m per Room vs. ¥12,900 ADR
• Kanpo no Yado to Kamenoi Hotel: 39 Hotels, +27% ADR After Renovation
• Citadines North Shinjuku: Ex-Hundred Stay to 179 Units in ¥30bn+ Deal
• What Is a Hotel Rebrand Opening? 3 Layers and 3 Measured 2026 Cases