Buildings & Classrooms - EmptyClassroom

Overview

EmptyClassroom currently tracks availability for 77 classrooms across two major Boston University buildings. Each building has its own operating hours and collection of classrooms available for study.

Supported Buildings

EmptyClassroom monitors classrooms in the following buildings:

CAS

College of Arts & Sciences

54 classrooms
Open 7 AM - 11 PM
Includes basement and upper-floor rooms

CGS

College of General Studies

23 classrooms
Open 7 AM - 9:30 PM
Multi-floor classroom building

College of Arts & Sciences (CAS)

Building Information

Building code: CAS
Full name: College of Arts & Sciences
Operating hours: 7:00 AM - 11:00 PM
Total classrooms tracked: 54

Classroom Distribution

CAS has a diverse mix of classroom types and locations:

Basement Level (B-prefix)

B06A, B06B - Split basement rooms
B12, B18, B20 - Basement classrooms
B25A, B25B - Additional split basement rooms
B27 - Basement classroom
B36 - Basement classroom

Basement classrooms often have the fewest conflicts and can be great for quiet study sessions.

First Floor

116 - Main level classroom
114A, 114B - Split first-floor rooms

Second Floor

201, 203, 208 - Standard 200-level rooms
204A, 204B - Split classrooms
211, 212, 213, 214, 216, 218, 220 - Sequential rooms
222, 223, 224, 225, 226, 227, 228, 229 - Upper 200-level rooms
233, 235, 237 - End of second floor

Third Floor

310, 312, 313, 314, 315, 316, 318, 320 - 300-level rooms
322, 323A, 323B, 324, 325, 326 - Additional 300-level rooms

Fourth Floor

424, 426, 427 - 400-level rooms

Fifth Floor

522 - Single 500-level room

Special Spaces

Tsai - Tsai Performance Center (auditorium-style)

CAS has the widest variety of room types, from small split classrooms (A/B variants) to larger lecture halls.

College of General Studies (CGS)

Building Information

Building code: CGS
Full name: College of General Studies
Operating hours: 7:00 AM - 9:30 PM
Total classrooms tracked: 23

CGS closes earlier than CAS (9:30 PM vs 11:00 PM). Plan your study sessions accordingly.

Classroom Distribution

CGS classrooms are organized across multiple floors:

First Floor

111A, 111B - Split first-floor rooms
113, 115 - Standard first-floor rooms
117A, 117B - Additional split rooms
121, 123, 129 - First-floor classrooms

Third Floor

311, 313, 315 - 300-level rooms
321, 323 - Additional 300-level rooms

Fourth Floor

421, 423 - 400-level rooms

Fifth Floor

505 - Single 500-level room
511, 515 - 500-level classrooms
521, 523, 525, 527 - Upper 500-level rooms

CGS has many split classrooms (A/B variants) on the first floor, which are often smaller and more intimate for individual or small-group study.

How Classrooms Are Displayed

Building Accordions

Classrooms are organized into expandable building sections:

Building header

Shows the full building name, code, and availability count (e.g., “College of Arts & Sciences - CAS” with “5 available”).

Availability badge

Green badge with count for available rooms, or red “unavailable” badge if none are free.

Chevron icon

Arrow that rotates when you expand/collapse the building section.

Classroom list

Inside each building, classrooms are listed with their availability time slots.

Classroom Cards

Each classroom displays:

Room name: Building code + room number (e.g., “CAS 225”)
Status indicator: Green dot (available now) or red dot (occupied)
Time slots: All available time periods for the day
Current slot highlight: Active time slot shown in green text

Intelligent Sorting

Classrooms are sorted using a smart algorithm:

Letter-prefixed rooms first (alphabetically)
- B06A, B06B, B12, B18, B20, B25A, B25B, B27, B36, Tsai
Numeric rooms second (numerically)
- 111, 113, 115, 116, 121, 201, 203, etc.
Suffixed rooms (by base number, then suffix)
- 111A before 111B
- 204A before 204B
- 323A before 323B

This ensures rooms are easy to locate and logically organized by floor and room number.

Availability Detection

EmptyClassroom determines classroom availability by:

Time Slot Matching

The system checks if the current time falls within any available time slot:

const isTimeSlotAvailable = (slot: TimeSlot): boolean => {
  const startTime = createTimeForToday(slot.start);
  const endTime = createTimeForToday(slot.end);
  
  return currentTime >= startTime && currentTime <= endTime;
};

Real-Time Updates

The interface updates every minute:

Green/red indicators reflect current availability
Active time slots are highlighted in green
Availability counts update automatically
No refresh needed during the current session

The minute-based update cycle is implemented in frontend/app/components/BuildingAccordion.tsx:15 using a smart setTimeout that syncs with clock minutes.

Gap Requirements

A classroom is considered “available” when:

There’s at least a 30-minute gap in the schedule
Configured as MIN_GAP_MINUTES = 28 (with 2-minute buffer) in backend/config.py:13
Time slots are calculated from BU’s official course schedule

Data Structure

Classrooms are defined in backend/config.py:21:

Building Configuration

BUILDINGS = {
    "CAS": {
        "code": "CAS",
        "name": "College of Arts & Sciences",
        "business_start_hour": 7,
        "business_end_hour": 23
    },
    "CGS": {
        "code": "CGS",
        "name": "College of General Studies",
        "business_start_hour": 7,
        "business_end_hour": 21.5
    }
}

Classroom Configuration

CLASSROOMS = {
    "342": {"id": "342", "name": "116", "building_code": "CAS"},
    "344": {"id": "344", "name": "201", "building_code": "CAS"},
    # ... 70+ more classrooms
}

The id field corresponds to BU’s internal room identifier, while name is the familiar room number students use.

Complete Classroom Lists

All CAS Classrooms

View all 37 CAS classrooms

116, 114A, 114B
201, 203, 204A, 204B, 208, 211, 212, 213, 214, 216, 218, 220, 222, 223, 224, 225, 226, 227, 228, 229, 233, 235, 237
310, 312, 313, 314, 315, 316, 318, 320, 322, 323A, 323B, 324, 325, 326
424, 426, 427
522
B06A, B06B, B12, B18, B20, B25A, B25B, B27, B36
Tsai

All CGS Classrooms

View all 22 CGS classrooms

111A, 111B, 113, 115, 117A, 117B, 121, 123, 129
311, 313, 315, 321, 323
421, 423
505, 511, 515, 521, 523, 525, 527

Future Building Additions

EmptyClassroom is designed to scale to additional buildings. The architecture supports:

Adding new buildings to the BUILDINGS configuration
Mapping classrooms to their respective buildings
Custom operating hours per building
Automatic integration with the search and filtering system

Want to request a new building? Use the Request form linked in the app footer.

Technical Implementation

Backend Organization

Classroom data is fetched from BU’s scheduling API and organized by building:

# Organize response by building
res = {}
for building_code, building_data in BUILDINGS.items():
    res[building_code] = {
        "code": building_data["code"],
        "name": building_data["name"],
        "classrooms": []
    }

# Add classroom data to buildings
for classroom_id, classroom_data in CLASSROOMS.items():
    building_code = classroom_data["building_code"]
    if building_code in res:
        res[building_code]["classrooms"].append({
            "id": classroom_data["id"],
            "name": classroom_data["name"],
            "availability": availability_data.get(classroom_id, [])
        })

This code is in backend/main.py:165.

Frontend Rendering

Buildings and classrooms are rendered using:

Radix UI Accordion for expandable building sections
React state management for tracking open/closed state
Real-time filtering based on search queries
Dynamic availability badges that update every minute

Implemented in frontend/app/components/BuildingAccordion.tsx:1.

Tips for Finding Classrooms

Explore basement rooms

CAS basement rooms (B-prefix) often have fewer classes scheduled and more availability.

Check both buildings

If one building is full, the other might have plenty of open rooms.

Mind the closing times

CGS closes at 9:30 PM, while CAS stays open until 11 PM for late-night studying.

Use split rooms

A/B rooms (111A/111B, 204A/204B) are often smaller and quieter.

Get Started

Features

Technical

API Reference

Contributing

​Overview

​Supported Buildings

CAS

CGS

​College of Arts & Sciences (CAS)

​Building Information

​Classroom Distribution

​Basement Level (B-prefix)

​First Floor

​Second Floor

​Third Floor

​Fourth Floor

​Fifth Floor

​Special Spaces

​College of General Studies (CGS)

​Building Information

​Classroom Distribution

​First Floor

​Third Floor

​Fourth Floor

​Fifth Floor

​How Classrooms Are Displayed

​Building Accordions

​Classroom Cards

​Intelligent Sorting

​Availability Detection

​Time Slot Matching

​Real-Time Updates

​Gap Requirements

​Data Structure

​Building Configuration

​Classroom Configuration

​Complete Classroom Lists

​All CAS Classrooms

​All CGS Classrooms

​Future Building Additions

​Technical Implementation

​Backend Organization

​Frontend Rendering

​Tips for Finding Classrooms

Explore basement rooms

Check both buildings

Mind the closing times

Use split rooms

Build docs developers (and LLMs) love

Overview

Supported Buildings

College of Arts & Sciences (CAS)

Building Information

Classroom Distribution

Basement Level (B-prefix)

First Floor

Second Floor

Third Floor

Fourth Floor

Fifth Floor

Special Spaces

College of General Studies (CGS)

Building Information

Classroom Distribution

First Floor

Third Floor

Fourth Floor

Fifth Floor

How Classrooms Are Displayed

Building Accordions

Classroom Cards

Intelligent Sorting

Availability Detection

Time Slot Matching

Real-Time Updates

Gap Requirements

Data Structure

Building Configuration

Classroom Configuration

Complete Classroom Lists

All CAS Classrooms

All CGS Classrooms

Future Building Additions

Technical Implementation

Backend Organization

Frontend Rendering

Tips for Finding Classrooms